Displaying items by tag: Comparative Anatomy

COMPARATIVE ANATOMY: EXCRETORY SYSTEM OF REPTILE, BIRD AND MAMMAL

15 Jul 2009

Lizard, bird and rabbit, all these three animals are included in group Amniota (Amniote). They excrete the unwanted nitrogenous waste products from their body, and the process is called excretion. If the process of excretion does not take place properly in the body, they become poisonous. In Vertebrates, main excretory organs are called as kidneys. Skin, gills, lungs, liver and intestine are also acts as accessory excretory organs.

Kidneys are located on the dorsal side of the coelom and they are made up with numerous uriniferous tubules.

Typical, uriniferous tubule is consist of three parts.

Ciliated peritoneal funnel
Malpighian body
Ciliated convoluted tube

EXCRETORY SYSTEM - GARDEN LIZARD	EXCRETORY SYSTEM - PIGEON	EXCRETORY SYSTEM - RABBIT
1. Paired kidneys are dark red and irregular in shape. These are flattened organs.	1. Kidneys are dark red and somewhat rectangular and flattened organs.	1. Kidneys are dark red and bean-shaped organs.
2. Kidneys are located in the posterior region of the abdominal cavity and attached to the dorsal wall by a fold of peritoneum.	2. Kidneys are situated in the anterior part of the abdomen.	2. Kidneys are located in the posterior part of the abdominal cavity.
3. Right and left kidneys are opposite to each other.	3. Same as in calotes.	3. The two kidneys are distinct. The right kidney lies much ahead than the left kidney.
4. They are attached to the dorsal muscles.	4. They are fitted in the hollows of the pelvic girdle.	4. Same as in calotes.
5. They are very near to the median line kidneys are Metanephros type.	5. They are a little away from the median line. Kidneys are Meta nephros type.	5. They are well away from the median line. Kidneys are meta ne phros type.
6. Each kidney has two lobes Anterior lobe is broad and posterior lobe is broad Hilus is absent.	6. Each kidney has three lobes They are anterior, median and posterior lobes. Hilus is absent.	6. Each kidney is a single-lobed structure. Inner side of the kidney has a concave depression is known as the 'hilus'.
7. The two kidneys are united posteriorly forming a V-shaped structure.	7. The two kidneys are separate and do not fuse with each other.	7. The two kidneys are distinct.
8. The two ureters are narrow, thin-walled ducts extending behind from the kidneys to the cloaca, where these open into the urodaeum.	8. Same as in Calotes.	8. The ureters open into the urinary bladder. Ureters arise from the hilus of each kidney.
9. There is no pelvis.	9. There is no pelvis.	9. Each ureter is expanded in its kidney into a funnel like pelvis.
10. In males the ureters join at its posterior end with its corresponding vas deferens and both open by a common urino-genital aperture.	10. The ureters do not join with the vas deferens and both open separately into the cloaca.	10. Ureters open separately into the urinary bladder.
11. A thin walled urinary bladder opens on the ventral side of cloaca.	11. Urinary bladder is absent.	11. Urinary bladder is a large, median, pear, shaped, thin walled transparent sac.
12. Urinary bladder communicates with urodaeum thrumph its ventral wall.	12. __	12. Urinary bladder opens into the urethra or unnogenital canal.
13. Calotes is uricotelic animal Urine consists n.ainly of uric acid.	13. Urine consists mainly of uric acid cotelic animal.	13. Urine consists mainly of urea - ureotelic animal.
14. Urine is excreted in a semi solid state.	14. Urine is excreted in a semisolid state (Bird droppinos).	14. Urine is passed out in a fluid state.

EXCRETORY SYSTEM OF FISH	EXCRETORY SYSTEM OF FROG
1. Paired kidneys are very long and ribbon like.	1. Paired kidneys are short and roughly oval in shape.
2. Each kidney is differentiated into a small non-renal part (genital part) and a long posterior renal part. The two parts exhibit morphological difference.	2. Each kidney possesses genital as well as renal region. But these are not morphologically differentiated.
3. The kidneys are uriniferous 'Opisthonephros' but functional Mesonephros.	3. The kidneys are mesonephros.
4. Some uriniferous tubules retain peritoneal funnel.	4. The peritoneal funnels are absent.
5. The uriniferous tubules have a specialised urea - absorbing segment.	5. The urea-absorbing segment is absent.
6. Uriniferous tubules lead into special tubes - the urinary ducts (ureters). These are distinct from wolffian ducts.	6. Uriniferous tubules lead into the wolffian ducts.
7. Ureters run back ward over the ventral surface of the kidneys.	7. Wolffian ducts leave outer border of kidneys and run backward.
8. Ureters are independent ducts to carry urine from the kidneys to the Urinogenital sinus'.	8. The ureters serve for the passage of genital elements as well as urine. So they are known as urino-genital ducts.Urino genital sinus is absent.
9. The urinary bladder is absent.	9. A large bilobed urinary bladder is present. It opens into the cloaca opposite the openings of the ureters.
10. The urine is hypotonic to blood.	10. The urine is hypertonic to blood.
11. Scoliodon is an ureotelic animal. The endproduct of nitrogen metabolism is urea. A large Quantity of urea is retained in the body as an adaptation to marine life.Excess of urea is excreted chiefly through its gills.	11. Frog is also ureotelic animal. It excretes urine from the cloaca in the form of urea.

VENOUS SYSTEM OF CALOTES (GARDEN LIZARD)	VENOUS SYSTEM OF COLUMBA (PIGEON)	VENOUS SYSTEM OF ORYCTOLAGUS (RABBIT)
1. The venous system consists of common pulmonary vein, two precaval and one post caval veins. These collect blood from the various parts of the body.	1. The venous system consists of three large veins-teeo precavak and one post caval along with four large pulmonary veins.	1. The venous system consists of four distinct divisions. i) System of venae carae ii) Hepatic portal system iii) Pulmonary system iv) Coronary system
2. The two precaval veins collect blood from the anterior part of the body. Each precaval is formed by the union of the internal and external jugular veins from head and the sub clavian vein from the arm. Transverse jugular vein is absent. Azygous vein is also absent.	2. The two precaval veins collect blood from the anterior part of the body. Each precaval vein is formed by the union of Jugular (head), brachial (arm) and pectoral (Pectoral muscfes) veins. Transverse jugular vessel is present in between the jugular veins. Azygous vein is absent.	2. The two precaval veins collect blood from the anterior part of the body. Each precaval vein is formed by the union of the external jugular vein (head) and subclavian vein (fore limb). The right precaval vein receives the azygous (unpaired) and intercostal veins (intercostal muscles and dorsal wall of theory). Left azygous vein is absent.
3. The post canal vein joins the posterior angle of the sinus venous. It forms by the union right and left efferent renal veins and brings blood from the posterior side.	3. The post caval vein is formed by the union of two large itac veins a tittle behind the liver.	3. The post caval vein is a large median vein. It stands at the cauda region (icaudal vein) and runs forward and receives blood in its course. The veins which join the posl caval vein are pairec ilio himbars, iliacs gonadial renal, anc hepatic.
4. The renal portal system collects blood from the posterior side of the body. Caudal vein bifurcates into two pelvic veins which . unite in front and form into the median anterior abdominal vein enters into the liver. Each pelvic vein joined by femoral, sciatic veins of that side. From the pelvic arise the renal portal veins which branch into capillaries in the substance of the kidneys coccygeo-mesenteric vein is absent.	4. Renal portal system is not well developed in pigeon caudal vein bifurcates into right and left renal portal veins (Hypo gastric veins) each of which enters the kidney. The hypogastric vein receives the Internal iliac vein abng with femoral & sciatic veins. At the bifurcation of the caudal vein into the two renal portal veins arise a median 'coccygeome-senteric vein'. It is characteristic of birds. The coccygeo- mesenteric vein joins the hepatic portal vein.	4. Renal portal system is completely absent in Rabbit.
5. The Hepatic portal vein collects blood from the alimentary canal and enters the liver and breaks upto capillaries.	5. The Hepatic portal vein collects bbod from the alimentary canal and emptied into the liver. From the Ever the blood is carried by the post caval vein through hepatic veins.	5. Same as in pigeon.
6. Epi gastric vein is absent.	6. Epi gastric vein returns the blood from the mesenteries and joins the hepatic veins. This vein corresponds to the abdominal vein of the frog.	6. Epi gastric vein is absent.
7. The right and left pulmonary veins bring pure blood from the right and left lungs and united into a common branch. Common pulmonary vein opens into the left auricle.	7. Four large pulmonary veins return blood from the posterior part of the left auricle.	7. A pair of pulmonary veins bring oxygenated blood from the lungs They unite by a common arch and open into the dorsal wall of the left auricle.
8. The right auricle receives deoxygenated blood through sinus venosus and left auricle possess oxygenated blood. In the partially divided ventricle the blood mixes to some extent.	8. The right side of the heart (right auricle & ventricle) receives de-oxygenated blood and left side folded with (left auricle & ventricle) oxygenated blood.	8. Same as in pigeon. Coronary veins collect deoxygenated blood from the wall of the heart. The coronary sinus opens into the right auricle through an aperture guarded by the Valve of The besius'. The opening is called as the 'formina of the The besius'.

FISH (SHARK) - VENOUS SYSTEM	FROG (RANA) - VENOUS SYSTEM
1. The venous system comprises a system of large thin walled sinuses which collect blood from the different body organs	1. The venous system comprises of thin walled tubular veins.
2. It consists of the following systems i) Anterior cardinal system ii) Posterior cardinal system iii) Hepatic porta! system iv) Ventral veins vi) Cutanecious system	2. It is divided into i) Anterior system of veins ii) Posterior system of veins iii) Portal systems.
3. The anterior cardinal system and the interior jugular sinuses collect blood from the head region through a number of sinuses.	3. The blood from the head region is collected by a pair of precoval veins. Each precaval vein is formed by External jugular, innominate and subclavian veins.
4. The blood from gills is collected by five pairs of dorsal nutrient sinuses and five pairs of ventral nutrient sinuses.	4.The blood from the lungs is collected by a pair of pulmonary veins.
5. The nutrient sinuses carry deoxygenated blood.	5. The pulmonary veins carry oxygenated blood.
6. The nutrient sinuses empty into anterior cardinal and interior jugular sinuses which inturn open into the ductus cuvieri. Thus the blood finally carried to the sinus venosus.	6. The pulmonary veins open into the left auricle.
7. From the posterior part of the body the blood is collected by i) a pair of posterior cardinal sinuses ii) a pair of lateral abdominal veins iii) a pair of brachial veins.	7. The blood from the posterior part of the body is collected by i) renal portal system and ii) Post caval vein.
8. The renal portal system includes the caudal vein and the renal postal veins & Iliac veins. The blood from the pelvic fins is not carried to the kidneys.	8. The renal portal system consists of veins hind limbs i.e. femoral, sciatic and renal portal veins. The caudal vein is absent.
9. It is absent.	9. A part of the blood from the hind-body is transported to the liyer by an anterior abdominal vein.
10. The blood from the kidneys is collected by renal veins which open into posterior cardinals, opening into the cuvierian sinus.	10. The blood from kidneys is collected by four pairs of renal veins which open into the post caval vein.
11. The brachial veins join the lateral abdominals to form sub clavian veins which open into the ductus cuvieri.	11. The brachial veins open into the precaval veins particularly into the subclavian veins.
12. Three pairs cutaneous veins collect blood from the muscles of skin and open into the cardinal sinuses, lateral abdominals and brachial veins.	12. The cutaneous veins are only one pair which join with muscular & brachial and finally open into the subclavian veins.
13. The venus blood does not enter the sinus venosus directly. But it is collected first by the cuvierian sinus present transversely.	13. The blood collected by the two precavals and one post caval veins directly enters into the sinus venosus.
14. The blood from the parts of the alimentary canal is collected by the Hepatic portal vein and empties into the liver and from there it is transported by Hepatic sinuses into the sinus venosus.	14. The Hepatic portal vein collects blood from the different parts of the alimentary canal and empties into the liver. From the blood is transported into the sinus venosus through the hepatic veins and post caval vein.

Calotes (Garden Lizard)	Columba (Pigeon)	Oryctolagus (Rabbit)
1. Arterial system consists of a pair of systemic arches and a pulmonary arch.	1. Arterial system consists of two arches-Right systemic arch and pulmonary arch. The right systemic arch is called Right Aortic arch.	1. Aiterial system consists of two arches, left systemic arch and pulmonary arch. The left systemic arch is known as Left aortic arch
2. The systemic arches and the pulmonary arch arise from the dorsal and ventral parts of the single ventricle. All the three arches are connected by connective tissue.	2. Right aortic arch arises from the left ventricle and pulmonary arch arises from the right ventricle.	2. Left aortic arch airses from the left ventricle and the pulmonary arch arises from the right ventricle.
3. The carotid branch of each side is connected with systemic arch by a vessel, 'Ductus caroticus'.	3. Ductus caroticus is absent.	3. Same is absent.
4. The subclavian arteries arise from the right systemic arch.	4.The right & left carotid and sub clavian arteries originate from the respective innominate arteries, ises.	4. The right carotid and sub clavian arteries arise from the innominate artery. But the left carotid and sub calvian arteries originate directly from the right aortic arch
5. Inter cestal arteries are present.	5. Same are present.	5. Same are present.
6. It is absent.	6. Pectoral artery supplies blood to the muscles of the wings.	6. It is absent.
7. Coeliac artery and anterior mesenteric artery arise separately from the dorsal from the dorsal aorta.	7. Same in pigeon.	7. Same in rabbit.
8. It is absent.	8. It is absent.	8. Phronic artery supplies blood to the muscles of the Diaphragm.
9. A pair of gonadial arteries are present.	9. From the anterior renal arteries the gonadial arteries are formed.	9. Paired Gonadial arteries arise directly from the dorsal arch.
10. Unpaired posterior mesenteric artery is present.	10. Same is present in pigeon.	10. Same is present in rabbit.
11. Three pairs of renal arteries arise from the dorsal aorta.	11. The anterior renal arteries develop from the dorsal aorta. But middle & posterior renal arteries arise from the sciatic artery of each side.	11. A pair of renal arteries arise from the dorsal aorta.
12. Common Iliac arteries are formed from the dorsal aorta.	12. The internal iliac arteries are formed from the dorsal aorta.	12. Iliolumbar arteries arise from the dorsal aorta.
13. The caudal artery is the terminal portion of the dorsal aorta to the tail.	13. The caudal artery the terminal portion of the dorsal aorta to the tail.	13. The caudal artery is the continuation of the dorsal aorta to the tail.
14. The pulmonary arteries carry blood from right part of the single ventricle to theright and left lungs.	14. Each pulmonary artery carries deoxygenated blood to the respective lung for purification.	14. The pulmonary artery which arises from the right ventricle divides into two branches and carry deoxygenated blood to the respective lungs.
15. Coronary arteries supply blood to the walls of the heart.	15. Coronary arteries supply blood to the walls of the heart of bird.	15. Coronary arteries supply blood to the walls of the heart.

Scoliodon (Fish)	Rana (Frog)
1. The arterial system consists of a ventral aorta, afferent and efferent branchials, dorsal aorta, and its branches and hypobranchials.	1. The arterial system consists of a truncus arteriosus, three pairs of aortic arches and the dorsal aorta & its branches.
2. Five pairs afferent branchial arteries are present.	2. Absent.
3. Efferent branchial system is associated with gill-slits along with the respective arteries.	3. Absent.
4. The arteries to the head are given off from the first pair of epibranchials and by the branches of dorsal aorta carotid labyrinth is absent.	4.The head is supplied blood by the branches. Carotid arteries arising from the truncus arteriosus. Carotid labyrinth is present.
5. Parietal arteries are present.	5. Parietal arteries are absent.
6. Hypobranchial plexus is present.	6. It is absent.
7. Dorsal aorta is formed by the union of epibranchial arteries of both the right and left sides.	7. The second branches of turncus, the systemic arches of the left and right sides unite to form the dorsal aorta.
8. Subclavian arteries arise from the dorsal aorta.	8. Sub clavian artery arises from each systemic arch.
9. Absent.	9. Occipito-vertebral artery arises from the systemic arch of each side.
10. Coeliaco-mesenteric artery arises from behind the union of the four pairs of epibranchials.	10. Coeliaco-mesenteric artery arises from the junction of the two system¬ic arches.
11. Just below the Coeliaco-mesenteric artery, lienogastric artery arises.	11. Lie no gastric artery is absent.
12. The parietal artery gives off four pairs renal arteries.	12. Four pairs of renal arteries arise directly from the dorsal aorta.
13. Gonadial (Spermatic or ovarian) artery arises from the lieno gastric artery.	13. Gonadial arteries arise directly from the first pair of renal arteries.
14. Dorsal aorta terminates into caudal artery.	14. C-iudal artery is absent.
15. Pulmo cutaneous arch is absent.	15. The third branch of truncus is the pulmo-cutaneous arch which is divided into pulmonary and cutanecious arteries.

Calotes (Lizard)	Columba (Pigeon)	Oryctolagus (Rabbit)
1. Heart is situated mid ventrally in the anterior part of the body cavity in the pleuro peritoneal cavity behind the sternum.	1. Same way the heart is located.	1. Heart is situated in the thoracic cavity, between the lungs of two sides (Mediastinum). It is present slightly towards the left side.
2. Heart is comparatively smaller in size.	2. Heart is comparatively larger in size.	2. Heart is comparatively larger in size.
3. It is enclosed by double walled pericardium.	3. It is also enclosed in the double walled pericardium.	3. Same.
4. Heart includes a dorsal sinusvenusus aright auricle, a left auricle and a single incom-pletely divided ventricle.	4. Heart is four chambered, sinus venosus is absent in the adult. Completed divided two auricles and two ventricles by inter auricular septum and inter ventricular septum respectively.	4. Same as in columba.
5. The three vena cavae or two precavals and a post caval vein open into the sinus venosus.	5. The three vena cavae or two precavals and a post caval empty the blood directly into the right auricle.	5. Same as in pigeon.
6. The left auricle receives two pulmonary veins from the lungs.	6. The left auricle receives four pulmonary veins from the lungs.	6. Left auricle receives two pulmonary veins from the lungs.
7. The right auricle possess sinu auricular aperture guarded by valve.	7. Absent.	7. Absent.
8. The two auricles are completely separated by inter auricular septum. But the inter ventricular septum in the ventricle is incomplete. Hence oxygenated and deoxygenated types of blood is mixed to some extent in the ventricle.	8. Complete inter auricular and inter ventricular septa are present. There is no possibility of mixing the oxygenated blood with deoxygenated blood.	8. Same as in pigeon.
9. The heart of lizard is in a transitional stage approcarhing the double circuit stage But it has not reached it completely due to incomplete division of the encircle.	9. The heart is a double circuit heart because of complete division of ventricle into right and left chambers.	9. Same as in pigeon.
10. The auriculo ventricular aperture is guarded by two flap like semilumar valves.	10. The right auriculo ventricular aperture is guarded by two large muscular flap like valve and the left by three valves.	10. The right auriculo-uentricular aperture is guarded by tricuspid valve and the left by bicuspid valve (mytral valve).
11. There are three aortic arches arising from the ventricle. Pulmonary trunk (ventral most) Right systemic trunk (arise from left side of ventricle)	11. Only two aortic arches originate from the ventricles. Pulmonary trunk (from right ventricle) Right systemic trunk (from left ventricle) i.e. Right aortic arch is characteristic of birds.	11. Only two aortic arches arise from the ventricles. Pulmonary arch (right ventricle) Left systemic aorta (Left aortic arch from the left ventricle). Right aortic arch is absent.
12. Ductus caroticus is present (connection between carotid & systemic arches)	12. Absent	12. Absent
13. Lizard's heart presents a transitional heart, since it approaches the double circuit heart but has not yet completely attained. So the heart is less efficient.	13. Avian heart has at tained maximum com olexity and is a double circuit heart, i.e. venous blood is com pletely separated frorr oxygenated blood.	13. Same as in Pigeon.
14. Absent.	14. Sinu-Auricular Node and Auriculo ventricular node are present.	14. SA - node and A.V. node are present. In addition bundle of His muscles are also develop.

FISH HEART (SCOLIODON)	FROG HEART (RANA)
1. Heart is approximately pear-shaped.	1. Heart is approximately pear-shaped.
2. The pericardial cavity is not wide and the pericardium forms double membrane around the heart.	2. The pericardial cavity is not wide and the pericardium forms double membrane around the heart.
3. The heart is formed of a dorsally placed sinus venosus and ventrally placed two auricle, a ventricle and truncus arteriosus or conus arteriosus.	3. The heart is formed of a dorsally placed sinus venosus and ventrally placed two auricle, a ventricle and truncus arteriosus or conus arteriosus.
4. The atrium or auricle is two-chambered and lies anterior to the ventricle. Auricles are separated by Inter auricular septum.	4. The atrium or auricle is two-chambered and lies anterior to the ventricle. Auricles are separated by Inter auricular septum.
5. The auriculo-ventricular valve is membranous.	5. The auriculo-ventricular valve is membranous.
6. The conus arteiiosus is incompletely divided by the spiral valve laterally into cavurn aorticum leading to carotid and systemic arches and the cavum pulmocutaneum leading to the pulmocutaneous arch.	6. The conus arteiiosus is incompletely divided by the spiral valve laterally into cavurn aorticum leading to carotid and systemic arches and the cavum pulmocutaneum leading to the pulmocutaneous arch.
7. The opening of the truncus with valves are arrenged in two transvarse rows.	7. The opening of the truncus with the ventricle is guarded by three semilunar valves arranged in a single row. They devide rruncus into a proximal pylangium and a distal synangium.
8. The walls of the auricle are thick.	8. The muscular walls of the auricle are thin.
9. The walls of the ventricle are highly muscular.	9. Same type of ventricle is present.
10. The lips of the bilaminate valves are connected to the inner surface of the ventricle is prominent part of the heart.	10. The membranous valves are connected to the inner surface of the ventricle by chordae-tendinae. Both auricles and ventricle are essential parts of the heart.
11. The fish heart is venous or branchial heart because it receives deoxygenated blood only.	11. The frog's heart receives both oxygenated and deoxygenated blood. The deoxygenated blood remain separate in the auricles but get mixed in the ventricle.
12. Blood passes only once through the heart in a complete circuit.	12. Blood passes through the heart twice in a complete circuit.
13. Such type of arrangement is absent.	13. The sinus venosus opens into the right auricle through simi-auricular aperture guarded by simi auricular valve which is also known as pace maker.
14. No separate vessel collects oxygenated blood since the heart is venous heart	14. The oxygenated blood is collected by pulmonary vein from lungs and carries into left auricle.

SKULL OF SCOLIODON (Shark)	SKULL OF RANA (Frog)	SKULL OF CALOTES (Garden Lizard)	SKULL OF COLUMBA (Pigeon)	SKULL OF ORYCTOLAGUA (Rabbit)
1. Skull is formed with cartilage tissues.	1. Skull is formed mostly with bony tissues (but tadpole skull is cartilaginous)	1. Skull is formed mostly with bony tissues.	1. Skull is formed mostly with bony tissue.	1. Skull is formed with mostly bony tissue.
2. It consists of cranium, sense capsules and visceral arches.	2. It consists of cranium, sense capsules, jaws and hyoid apparatus.	2. It consists of cranium, sense capsules, jaws and hyoid apparatus.	2. Same as in calotes.	2. Same as in calotes.
3. It is the axial portion of the skull. It is more or less a violin box open in front and behind with an arched roof and flattened floor. It is divided into occipital, auditory, orbital and ethmoidal regions.	3. It forms the middle hollow part of the skull. It is divided into auditory, olfactory and occipital regions.	3. It forms the median hollow part of the skull. It is divided into occipital, auditory, orbital, olfactory and optic regions.	3. It forms the posterior median hollow part of the skull. It is divided into occipital, auditory, optic orbital and olfactory regions.	3. It forms the middle hollow part of the skull. It is divided into occipital auditory, optic orbital & olfactory regions.
4. Foramen magnum is posteriorly present.	4. Same.	4. Same.	4. Same.	4. Same.
5. Beneath the foramen magnum a deep concavity is present. On either side of this concavity is a prominence - occipital condyle articulates with the first vertebra, occipital crest is formed. Dicondylic skull.	5. Beneath the foramen magnum there are two occipital condyles. On either side of the foramen magnum dorsolaterally exoccipital bones are present. Dicondylic skull	5. Beneath the foramen magnum a single occipital condyle is present.suupraoccipitai, exo occipitals,& basi occipital bones are also present in the occipital region. Monocondylic skull.	5. Beneath the foramen magnum single occipital condyle is present. Supra occipital, Exocci pitals & basioccipital bones are also present. Monocondylic skull.	5. Beneath the foramen magnum two occipital condyles with paroccipital process are present. Supraoccipital, exo-ccipitai, & basio-ccipital bones are also present. Dicondylic skull.
6. Auditory region has a mid dorsal depression - parietal fossa. It contain two pairs of apertures. Anteriorly smaller openings of endolymphatic ducts and posteriorly larger openings of perilymphatic spaces are present.	6.—	6.—	6.—	6.—
7. Auditory capsules lie on the poster lateral sides of the cranium. Which enclose & protect the ears. Post orbital groove is present on the ventral side	7. Auditory capsules enclose the internal ear. Its roof is formed by pro-otic bone, fenestra ovalis, stapedial plate and columella auris are present.	7. Each auditory capsule is formed by small, single vertical prootic bone which is lying outside the supra occipital. Epiotic & opisthotic are not differentiated.	7. Each auditory capsule is formed largely by the prooticbone. Fenestra ovalis, fenestra rotun da, columella auris, stapes are also present.	7. Each auditory capsule in the adult animal consists only periotic. Flask - like Tympanic bulla bone is significant.
8.—	8. Dorsally the cranium is formed, by frontoparietals, ventrally by parasphenoid and laterally by sphen ethmoid bones.	8. The dorsal part of the cranium is formed by parietals, frontals interparietal foramen, and ventrally by basisphenoid, parasphenoid bones.	8. The dorsal part of the cranium is formed by Parietals, frontals a rostum, alisphenoids; ventrally basisphenoid, basitemporal bones.	8. The cranium is formed dorsally by 'Parietals, frontals, inter parietal, and ventrally by basisphenoids, presphenoid bones along with alisphenoids and orbit sphenoids. The cranial cavity is closed infront by a narrow vertical bone cibriform plate.
9. Each orbit lies on the sides of the middle part of the cranium. It is bordered by dorsal super orbital ridge,anterior preorbital process, posterior post orbital process and ventraily by infra orbital ridge. The orbital region has a large oral cavity anterior fontanelle.	9. On either side of the cranium is large gap - orbit which lodges the eye.	9. In the middle of the cranium laterally two orbits are present. Each orbit is bounded by prefrontal supra orbital, lacrimal, post frontal and jugal bones. The jugal bone forms the ventral border of the orbit. Supratemporal arch is present.	9. The two orbits are very large cavities present infront of the cranium. Each orbit is bounded dorsally by frontal, antero - dorsally by lacrimal and posteriorly by the zygomatic process. Orbit is incomplete on the ventral side. The two orbits are separated by inter orbital septum.	9. These are two orbits are large sockets present on the sides of frontal segment of cranium. The orbit is bounded dorsally by frontal, anteriorly by maxilla and lacrimal, posteriorly by squamosal and alisp-henoid and externally by the zygomatic arch.
10. The olfactory capsules lie at the anterior side of the cranium. Each capsule possesses a short sic at ethmopalatine ridge.	10. The olfactory capsules are separated, from each other by mesethmoid. Each capsule is formed by a large triangular nasal on the dorsal side and a smaller triradiate vomer on the ventral side vomers possess vomerine teeth.	10. Each olfactory capsule is formed by three bones Nasal, septo maxillary and vomer.	10. Each olfactory capsule is formed by two bones - Nasal and vomer. Nasals fuse with frontals and form into super and inferior processes.	10. Each olfactory capsule is bounded by dorsally by long nasal bone and laterally by jaw bones. The two capsules are separated by mesethmoid bone. The lower end of mesethmoid fits into a vomer bone. Vomer is formed by the fusion of a pair of bones.
11. Ethmoidal region tapers anteriorly. It consists of a basal slender barventro-median rostral cartilage and a pair of similar barsdorso - lateral rostral cartilages arisen from the roof of ihe olfactory capsules.	11. Absent.	11. Absent.	11. Absent.	11. Absent.
12. Scoliodon has seven visceral arches which are cartilagienous. The first arch forms the jaws and it is catted Mandibular arch the second one is the hyoid arch the remaining five arches are called branchial arches.	12. Branchial arches are absent.There are upper and lower jaws to support the borders of the mouth. The upper jaw is formed by union of two similar halves. Each half is formed by the Pre-maxilla, maxilla and quadratojugal. The inner set of the jaw has palatine, ptery goid and squamosal bones. The lower consists of two halves and unite anteriorly by mento-meckelian cartilage. Each half consists of dentary and angio -splenial bones. Just infroni of the articular fact a small coro-nary process is present. Upper jaw alone has teeth.	12. Branchial arches are absent.	12. Branchial arches are absent.	12. Branchial arches absent.These are upper and lower jaws. Each half of the upper jaw is formed by premax-illa, maxilla jugular, palatine, pterygoid and squamosal.
13. The mandibular arch consists of two halves. Each half of this arch possess an upper paleto-pterygo quadrate cartilage and a lower meckel s cartilage.The pale topterygo Quadrate gives off anteriorly palatine. The two sides of it from the upper jaw with teeth. The two meckel's cartilages united antero medially by ligament form the lower jaw with teeth.		13. These are upper and lower jaws. Each half of the upper jaw consists of an outer set of bones - pre maxilla, maxilla, jugal and quadrate and the inner set includes pterygoid, palatine, transp-alatine, epiptery-goid and squamosal. Each half of the lower jaw consists of six bones -dentary, angular, supra angular, articular, splenial and coronoid. Both the jaws possess teeth.	13. These are upper and lower jaws. Each half of the upper jaw is formed by premaxilla, maxilla, quadra tojugal, and jugal bones. The inner arcade of the upper jaw forms the roof of bucco pharyngal cavity which consists of palatine, pterygoid, and quadrate. Each half of the lower jaw is formed by articular, angular supra angular, dentary and splenial. Both the jaws are lacking the teeth.	13. The lower jaw also consists of two halves. Each half is formed by a single, large dentary bone. The posterior of the dentary possess condylar, coronoid and angular process. Both the jaws possess the codent type of teeth which are having different (Heterodont teeth in mammals) shapes. Diastema is present in both the jaws because of the absence of canines.
14. Hyostylic jaw suspension.	14. Auto stylic jaw suspension.	14. Auto stylic jaw suspension.	14. Auto stylic jaw suspension.	14. Craniostylic jaw suspension.

Shark (Scoliodon)	Frog (Rana)
1. The pelvic girdle is formed with cartilage tissues.	1. The pelvic girdle is formed chiefly with bone tissues.
2. It is embeded in the body wall muscles infront of the cloacal aperture.	2. It is present at the hind end of the trunk.
3. It is a simple transverse bar known as ischio - pubis bar.	3. It consists of two similar halves which are separated infront and fused behind to form a median vertical disc.
4. Each half of the girdle is formed by the fusion of ilium ischium and pubis.	4. Each half of the girdle consists of three bones - ilium, isclium and pubis.
5. Acetabulum is absent.	5. Each side of the vertical disc bears a cup-like depression Acetabulum. The head of femur of the thigh bone articulates with the acetabulum. So all the three bones take part in the formation of the acetabulum.
6. The ilium possess an iliac process and a foramen.	6. The ilium extends forwards in the form of an arm to articulate with the transverse process of the sacral vertebra. A vertical ridge is formed along with this arm is called iliac crest.
7. Ischium and pubis fused together and form Ischio-pubis bar.	7. The ischium forms the posterior part of the disc and acetabulum. Ischium, fuses with the other side ischium and forms ischium symphysis.
8. Pubis fuses with ischium. It is not a separate bone.	8. The pubis forms the ventral part of the disc and acetabulum. It fuses with the pubis of the other half and forms pubic symphysis. It is a separate bone.
9. Pubis is formed with cartilage tissue.	9. Pubis is formed with calcified cartilage tissue.
10. The pelvic girdle is straight in the middle but bent at the ends. These are produced dorso-lat-erally into short iliac processes.	10. The pelvic girdle V-shaped associated with a vertical disc formed with the ischium & pubis bones.
11. The pelvic fins are attached directly.	11. The hind limb bones are articulating with the pelvic girdle.
12. The pelvic girdle provides attachment to the claspers through the muscles of male.	12. Such arrangement is absent. Penis is absent.

Shark (Scoliodon) - Pectoral Girdle	Frog (Rana) - Pectoral Girdle
1. Pectoral girdle is present in the body wall muscles below the last branchial arch.	1. Pectoral girdle is present in the anterior part ot the trunk.
2. It is not connected to the axial skeleton and formed with cartilage tissues only.	2. It is connected to the axial skeleton (vertebral column) dorsally with muscles & ligaments and formed mostly with bone tissues.
3. Pectoral girdle has two halves.	3. Same as in shark.
4. The osinnominatum has a thin flat, ventral coracoid and a thick rod-like dorsal scapula along with clavicle bones. This type of girdle is known as scapulo-coracoid bar. Supra scapula is absent.	4. The os innominatum has the dorsal scapular part and ventral coracoid part. Stouter scapula on the lateral side and the supra scapula formed of calcified cartilage which is a* thin, broad present on the dorsal side. The clavicle membrane bone is present antero-ventral to the pectoral girdle.
5. The coracoid bone is poorly developed and present on the ventral side. It is not differentiated into pre, and epi coracoids.	5. The coracoid part possess, proper stout uralid, infront of it calcified cartilaginous pre coracoid along with another strip cartilaginous epicoracoid bones. The two epicoracoids are closely associated with each other in the mid ventral line.
6. Glenoid cavity is absent.	6. At the junction of scapular & coracoid bones on the posterior side, the depression of glenoid cavity is present.
7. Sternum is absent.	7. The sternum lies in the mid ventral line of the chest part. It has two portions. The anterior presternum attached to the anterior part of the girdle. It possess a X - shaped omosternumand at its distal end a small carlilaginous episternum. The posterior purt sternum is present behind the girdle. It consists of a stout bone mesosternum and flat plate xiphisternum at the distal end.
8. The basal cartilages of the pec-toral fin are articulating with the pectoral girdle.	8. The forelimb bones are articulating with pectoral girdle.
9. Coracoid bones bear on its part a few formina for blood vessels.	9. Coracoid fenestrae are present.
10. It helps only for the movements of the pectoral fins and also protects the heart.	10. It not only helps the movements of the fore limbs but also protects the heart and lungs.

CALOTES SKIN (REPTILE INTEGUMENT)	COLUMBA SKIN (BIRD INTEGUMENT)	ORYCTOLAGUS SKIN (MAMMAL INTEGUMENT)
1. In Calotes (Reptile) the skin is rough, thick, dry and scaly. Skin is suited to the terrestrial environment which prevents any loss of water.	1. In birds the Skin is thin, loose and dry.	1. In Mammals Skin is thick, elastic and water proof.
2. Epidermis has a heavily cornified stratum, corneum which produce into hormy epidermal scales.	2. The epidermis is thin and delicate all over the body except on sharks and feet where it is thick and produce epidermal scales.	2. The epidermal cells form into four layers - Stratum corneum, S. lucidum, S. granulo sum & stratum.
3. The exoskeleton of scales is periodically cast off either in fragments or as a sin' gle piece. In turtles & tortoises the epidermal bony plates are formed. In others the scales are modified into shields, scutes, spines etc.	3. The exo Keleton is in the form leathers which are formed from structure corneum & stratum malpighii. The feathers are keratinised.	3. The epidermis also forms Sebaceous and sweat glands. The mucous glands are absent. The sweat glands help in excretion and maintain constant body temperature. Sebaceous glands secrete 'sebum' which lubricates the skin and hairs. Hairs are present.
4. The glands are practically absent. The only glands present are 'scent glands'.	4. The epidermis is devoid of glands except the single "uropygial gland" present at the base of the tail. The oily secre¬tion of the glard is used for preening the leathers.	4. Presence of mammary glands is the characteristic of mammals (Rifled sebaceous glands.)
5. Dermis is thick having stratum spongiosum & stratum com pactum.	5. Two layers are present in the dermis which is thin. Vascular layer is present in between the two layers.	5. Dermis is very thick. It has intricate system of connective tissue fibres extending in all directions.
6. Stratum spongiosum has numerous chromatophores. They exhibit wide colour patterns.	6. Chromatophoresare absent. But the pigment is found in the feathers and scales.	6. Chromatophores are absent large dendritic melanophores are present.
7. Sensory corpuscles are absent.	7. Cutaneous receptors are present in the dermis.	7. Numerous tactile corpuscles are highly developed.
8. Fat cells are not present in the dermis. Femoral glands are present.	8. Fat cells are present in the dermis.	8. Subcutaneous layer is formed of adipose tissue (Fat cells).
9. Distal ends of the digits have nails or claws which formed from the homy epidermis. These grow parallel to the surface of skin and formed of a dorsal plate 'unguis' (nailplate) and a ventral plate sub unguis (sole plate).	9. Similar claws are with unguis in the form of a long plate of keratin sharply curved and subunguis lies between its two edges.	9. Nails & hoofs are found. At the base of the nail, the epidermis is invaginated to form nailgroove and its part covering the nail root-eponychium.
10. Horny teeth are present which are acrodont or pleurodont Similar claws are with unguis in the form of a long plate of keratin.	10. Beaks are formed of enlarged epidermal scales which form hard keratinized covering over the jaw bones.	10. Hairs are keratin derivatives and exclusively present in mammals. These are strictly epidermal structures developed from stratum malpighii.

Scoliodon (Fish) - Skin	Rana (Frog) - Skin
1. Skin is rough & tough. It is firmly attached to the underlying muscles.	1. Skin is soft, smooth and loose. It is separated from the underlying muscles by lymph sacs.
2. The skin is divided into epidermis and dermis.	2. Same.
3. The epidermis is composed of many layers of similar epithelial cells. Stratum corneum is absent.	3. The epidermis is distinguished into stratum corneum and stratum malpighii.
4. Unicellular mucous glands are present in the dermis.	4. Mucous glands or cutaneous glands are multicellular and are present in the dermis.
5. Dermis is less vascularised.	5. Dermis is richly vascularised.
6. The skin is protective and sensory in function.	6. Skin is protective, sensory and respiratory (Cutaneous respiration) in function.
7. Placoid scales are present.	7. Scales are absent.
8. Dermis has no layers.	8. Dermis has stratum spongiosum & stratum compactum.
9. In the dermis chromatophore and iridocytes are present.	9. Chromatophores are found in the upper part of dermis. These help in changing the colour of integument.
10. In some deep-sea fishes light emiting photophores are present.	10. In some frogs (Bufo) poison glands are present near the tympanum.

Male Reproductive System
RABBIT	FROG
1. Sexual dimorphism is well marked due to presence of penis and scrotal sacs containing tests only in male.	1. Not distinct. However, in male frog, base of first inner finger forms a thick nuptial pad during breeding season to clasp female in amplexus. Vocal sacs present in males.
2. Include 2 testes,2 epididymes, 2vasa deferentia, urethra, penis and some accessory glands.	2. Include two testes, several vasa efferentia, bidders canal two urinogenital ductsand cloaca.
3. Small, oval, white bodies. Remain inside abdominal cavity in young. But descend from abdomen in to scrotal sacs during breeding season in adult.	3. Ovoid or rod-like, light yellow, attached to anteroventral surface of kidneys by mesorchium.
4. Rectal gland present..	4. Rectal gland absent.
5. Each testes attached by anterior end to dorsal abdominal wall by a sperma-tic cord and by posterior end to wall of scrotal sac by gubernaculum.	5. Absent
6. Epididymis well developed and has 3 distinct parts, caput, cauda and corpus epididymes attached to the anterior, posterior and inner sides, respectively, of testis.	6. Vas deferens does not form an epididymis.
7. Two vasa deferentia, arising from cauda epididymis of their side, open into neck of urinary bladder or urethra.	7. Each vas dererens unites with ureter of its side forming a urinogenital duct, opening separately into roof of cloaca.
8. Small, slightly bifurcated blind sac, called uterus masculinus or seminal vesicle opens dorsally and independently into urethra.	8. In some species of frog, terminal part of urinogenital duct enlarges forming a temporary seminal vesicle.
9. It includes small erectile cylindrical penis in front of anus of male. It serves to transmit sperms into vagina of female during copulaiton.	9. Copulatory apparatus absent. Fertilization external, inwater, where ova and spermatozoa are shed during amplexus.
10. Male has one pair of prostate, Cowper's, perenial andrectal glands. Their secretions either attract the female or contribute to semen.	10. Do not occur.

Rabbit		Frog
1. Omnivorous		1. Carnivorous
2. Alimentary canal consists of		2. Alimentary canal consists of i. Mouth
i. Mouth		ii. Buccal cavity
ii. Buccopharyngeal cavity		iii. Pharynx
iii. Pharynx		iv. Oesophagus
iv. Oesophagus		v. Stomach
v. Stomach		a. Cardiac part
a. Cardiac part		b. Fundic part absent
b. Fundic part		c. Pyloric part
c. Pyloric part		vi. Small intestine
vi. Small intestine: a. Duodenum b. Jejunum c. Ileum		a. Duodenum b. Absent c. Ileum vii. Large intestine or rectum
vii. Sacculus rotundus in rabbit		viii. Cloaca
viii. Caecum, Vermiform appendix		ix. Anus
ix. Colon
x. Rectum
3. Glands of alimentary canal are i. Salivary glands ii. Mucous glands iii. Gastric glands iv. Intestinal glands		3. Glands of the alimentary canal are the following: i. Mucous glands ii. Gastric glands iii. Intestinal glands
4. Accessory digestive glands i. Liver ii. Pancreas		4. Accessory digestive glands i. Liver ii. Pancreas
5. Mouth opens laterally and is surrounded by lips.		5. Mouth opens laterally. It opens and closes by the lowering and raising of the lower jaw as in all other higher vertebrates.
6. Teeth are in 2 sets i.e., milk teeth and permanent teeth. This type of teeth is called diphyodont. Teeth are with roots found in sockets and, therefore, are called thecodont. They are of different types, therefore, are called heterodont The dental formula		6. Teeth are present on upper jaw only. Teeth resemble those of Scoiiodon and are homodont, and pleurodont. Vomerine teeth present.
7.• Mouth leads into the mouth-cavity - the space between mouth and pharynx. It is supported by jaws. • Cheeks are situated at the sides while tongue is on the floor and palate forms roof. • Tongue is very muscular and is provided with ridged and rough surface. • It mixes with the saliva secreted by salivary glands. On the surface taste - buds are also found.		7. • Mouth opens into the mouth1 cavity, which is continued into pharynx. • Tongue is bifid, attached to the anterior part of the mouth cavity. Salivary glands are not found.
8. Oesophagus is a slender straight tube, which leads on the pharynx to the stomach.It also secretes mucus, which helps in lubricating the food.		8. Oesophagus is not sharply distinguished from either mouth or the stomach. Mucous glands are found in oesophagus.
9. Stomach is pear-shaped. Large, circular structure. It is distinguished into three parts - the cardiac part, the fundic part and the pyloric part.There are three types of gastric glands. a. Cardiac b. Fundic c. pyloric.		9. The stomach is a simple tube and consists of cardiac and pyloric. Gastric glands are present in stomach. Pyloric sphincter is also present, which separates stomach from intestine.
10. Length of the small intestine is greater and it is much coiled. The small intestine is provided with a large number of villi. There is also a ileo-coelic valve between the small intestine and the large intestine		10. Intestine is small. Its lining is not provided with either scroll valveorvilli. Duodenum is a U-shaped structure Small intestine is in a few coils.
11. There is also a caecum with scroll valve which is the first part of the large intestine. At the terminal end of the caecum is an appendix. Colon is followed by rectum.		11. Large intestine through rectum leads into the cloaca. There is a great distinction between large intestine and small intestine.
12. Liver is the largest digestive gland. In rabbit it is five-lobed. The bile-duct receives branches from each lobe.The bile from bileducts is poured into the duodenum.Glisson's capsule is present.		12. Liver is well-developed, made up of 3 lobes. Gallbladder is a rounded sac which stores bile. Common bile-duct is opens into the duodenum.
13. Pancreas is a diffused gland with small lobules. There are several pancreatic ducts, which open into the bile-duct.Pancreas is endocrine gland. In it are islets of langerhans. which produce insulin.		13. Pancreas is a cream-coloured, compact gland made up of small lobes situated between stomach and through the pancreas, called common bile-duct or hepatopan-creatic duct.

Scoliodon (Shark)	Rana (Frog)
1. Scoliodon performs branchial respiration.	1. Rana is adapted for branchial (Tadpole) as well as pulmonary respiration.
2. Respiration is performed by the gills. Skin, and bucco-pharyngeal lining are not respiratory. Lungs are absent.	2. Respiration is performed by the skin,bucco-pharyngeal lining and lungs.There are no gills in the adult.
3. It possess five pairs of internal gills located in the pleural walk of the pharynx. The external gills are absent. But gills are exposedoutside as external gill-slits.	3. Tadpole larva possesses three pairs of external gills in the early stages which are present at the junction of head and trunk. Later these are replaced by three pairs of internal gills.The adult possess the lungs.
4. Respiratory tract consists of mouth, buccal cavity, pharynx, internal branchial apertures, branchial pouches and external branchial apertures.	4. Respiratory tract consists of external nostrils, nasal chambers, internal nostrils, bucco-pharyngeal cavity, glottis and laryngo tracheal chamber. Which open into the lungs.
5. External nostrils, nasal chambers are not used in respiration. Internal nostrils glottis, and laryngo tracheal are absent.	5. Mouth is not used in respiration. Branchial apertures and pouches are absent.
6. The gills have cartilagenous gill arches to support the gill-axes.	6. Such type of organs are absent.
7. The gills are endodermal in origin and are formed by the outpushing of hypoblast.	7. Lungs are also endodermal in origin.
#####################################	8. Such an arrangement is absent in the adult frog.
9. Generally these are pairs of gill pouches one pair of hemi branches on the posterior side of the hy-oid arch and four pairs of holo branches on the 1st, 2nd, 3rd and 4th branchial arches. The 5th branchial arch is abranch.	9. Absent in the adult frog.
10. The gills-remain in well within the gill pouches.	10. Absent in the adult frog.
11. Absent in shark.	11. The larynx and trachea united and form into laryngo tracheal chamber which is supported by three cartilages a cricoid and a pair of lateralary tenoids.
12. Lungs are absent in shark.	12. Paired lungs are simple, thin-walled elastic sacs having on the inner surface low ridges the septa enclosing the alveoli.
13. No such arrangement is present.	13. The septa and alveoli increase the area coming in contact with air. Exchange of gases takes place all over the inner surface of the lungs.
14. During breathing, the buccal flow is lowered by coracohyal and coracobrachial muscles and raised by constrictor muscles.	14. During breathing, the bucco-pha-ryngeal flow is lowered by the sternohyal muscles and raised by the petrohyal muscles.
15. Water enters the respiratory tract through the mouth and leaves through the external branchial apertures. During this water flow, the dissolved oxygen in the water is absorbed and supplied to the blood in the gills.	15. Air enters the respiratory tract through the external nostrils and leaves also through the external nostrils after providing oxygen to the blood in the buccopharyngeal lining and lungs.
16. The blood is transported to the gills by five pairs of afferent branchial vessels.	16. The blood is transported to the lungs, skin and bucco pharyngeal cavity by the respective arteries.
17. Oxygenated blood from the gills is supplied to the body by nine pairs of efferent branchial vessels.	17. Oxygenated blood from the lungs, skin, and buccopharyngeal cavity is transported to the heart by the respective veins.

Calotes (Lizard)	Columba (Pigeon)	Oryctoiagus (Rabbit)
1. Mouth is a wide, slit present at the anterior end of head.	1. Mouth is terminal, slitlike aperture bounded by horny Jaws.	1. Mouth is sub-terminal, cleft bounded bv mobile, fleshy lips.
2. Buccal cavity is a narrow gap. Labial glands are present on lips.They secrete mucous.	2. Buccal cavity is narrow and some what and dorsoventrally flattened.	2. Buccal cavity is a spacious chamber andits space between lips and the teeth is called vestibule. This receives the mouth opening.
3. On both jaws teet are present, polyphyodont homodont teeth arranged in a single row on each jaw. Teeth are not useful for mastication. Pleurodont dentition is present.	3. Jaws are modified into tooth less beak.	3. Dentition in mammals:Teeth are diphyodont, heterodont and thecodont. These are arranged in a single row on each Jaw.Teeth are modified cutting (Incissors) and chewing (Premolars & molars) canines are absent in rabbit.
4. Tongue is attached posteriorly to the floor of buccal cavity and is free anteriorly. Sensory papillae are present.	4. Tongue is narrow triangular and fleshy. Its surface is covered with horny material and bears thorn-like projections which carry taste buds and mucous glands.	4. Tongue is highly specialized, fleshy and muscular and can be moved in different directions. It can be protruded out. Its surface is rugose being covered with numerous papillae along with taste buds.
5. A pair of internal nostrils open into the roof of the buccal cavity anteriorly. Hard palate is present.	5. A bony palate is wanting in birds but a pair of palatal folds and palatal groove between the two folds are present. Internal nostrils are located dorsal to the palatal folds.	5. The nasal passages are separated from the buccal cavity by a bony palate. The internal nostrils open into the pharynx nearer to glottis.
6. A bony palate is present covering the roof of the buccal cavity.	6. A bony palate is absent. But soft palate is formed of two membranous folds.	6. The palate is differentiated into anterior bony hard palate and a soft palate is formed of connective tissue. The soft palate is produced behind into a process – velum palati hanging down from the roof, which prevents the entry of food into nasal passage.
7. Unicellular mucous glands are present and keep the buccal cavity always wet.	7. Unicellular mucous glands are absent in the epithelium of bucco-pharyngeal region.	7. Unicellular mucous glands are absent. But multi cellular serous glands are present.
8. Salivary glands are absent. But labial glands are open at the lips which do not play any role in digestion.	8. Salivary glands which open into the buccal cavity are lingual, mandibular, maxillary, cricoary tenoid, palatinal and sphenopalatinal glands.	8. The multi cellular salaivary glands are four pairs. They are Infra orbital, parotid, sublingual and sub-maxillary glands. Palatine, tonsillar, superior & inferior labial glands are also associated.
9. Pharynx is marked off. On the roof of pharynx near the junction of two jaws a pair of openings is called Eustachian apertures. The floor of pharynx has the glottis.	9. Pharynx is marked off from the buccal cavity but it receives, internal nostrils through which nasal passages open into its cavity, the gullet & glottis.	9. Pharynx is not sharply demarcated from the buccal cavity. It receives the openings of esophagus and the glottis.
10. Esophagus is a narrow tube and straight extends through the neck. Mucous glands are present.	10. Oesophagus is a bng and narrow tube. It has thick walls. Mucous glands are absent.	10. Oesophagus is a long thin walled tube. It is clearly marked off from the pharynx as well as stomach. Mucous glands are present.
11. Crop is absent.	11. The oesophagus is dilated into a thin-walled sac the crop. It secrete pigeon milk in both sexes and used to feed the young birds.	11. Crop is absent. The wall of oesophagus is produced into the cardiac stomach to form cardiac valve.
12. Stomach is a sac- like structure. Its anterior part is cardiac stomach and posterior part is pyloric stomach. At the end of pyloric stomach a small constriction is present. It possesses a pyloric sphincter.	12. Stomach is divided into a glandular proventriculus and posterior muscular gizzard. Gizzard acts like grinding apparatus. Pyloric valve absent.	12. Stomach is divisible into cardiac, fundic and pyloric parts. Pyloric stomach contains pyloric valve.
	13. Intestine is differentiated into duodenum and ileum. Intestine very long and very much coiled because is a herbivorous animal	13. Same structures are present. But the bile duct and pancreatic ducts open separately into the proximal and distal ends of the duodenum respectively.
14. A single rectal caecum is present.	14. At the junction of ileum & colon, two divertulae are present. These are called Rectaicaeca.	14. An ilio-colic valve is present at the junction of the small intestine and large intestine or colon. At the junction of these portions, a spiral shaped vermi form appendix is present. At the regular intervals of the colon shows pocket-like pouches - 'Haustra'.Colon shows longitudinal muscle folds taeniae'. Cellulose enzyme is produced.
15. Cloaca is common opening for digestive'and urinogenital ducts. It is divided into coprodaeum, urodaeum, and proctodaeum.	15. Cloaca is large and divided into the same parts. On the dorsal side of the proctodaeum a thick walled blindsa "Bursa fabricii" is present. It becomes degenerated in the adult and is known as cloacal thymus.	15. Cloaca is absent. Anus is present.
16. Liver is bilobed gland. The right lobe has a gall bladder. It secretes bile (alkaline& no enzymes).	16. Liver is bilobed dark red gland. Gall Bladder is absent. Separate bile ducts are formed.Liver secretes bile.	16. Liver is very large and consists of five lobes. Kupffer's cells are present in the liver. Liver secretes bile. Gall Bladder is present.
17. Pancreas is a whitish gland present between stomach duodenum.	17. Pancreas is a pink coloured gland present the loop of duodenum. Three pancre catic ducts open into the duodenum.	17. pancreas is a diffused gland of pink colour. Pancreatic duct opens into the duodenum.
18. Gastric, intestinal glands are also present.	18. Same are present.	18. Same are present.

Myxine (Hagfish)	Petromyzon (Lamprey)
1. Hag fishes are scavengers. They penetrate into the dead fishes bodies and eat the tissues.	1. They are semi parasitic. But the Larvae(Ammocoetes) leads an independent life.
2. The body is. slender & eel-like	2. The body is cylindrical & stout.
3. They are exclusively marine habitats.	3. These live in both in sea water and fresh water. They migrate into the rivers for spawning.
4. the caudal fin is small.	4. The caudal fin is well developed.
5. The dorsal fin is not fully developed.	5. The dorsal fin is divided into two portions by a notch.
6. Mouth is terminal in position. It is surrounded by soft lips. Buccal funnel is absent.	6. Mouth is sub-terminal in position. Buccal funnel is present.
7. Single nostril is present very near to the mouth.	7. Single nostril Is on the dorsal side of head region.
8. Skull has no roof.	8. Skull roc is incomplete.
9. Small teeth are present on the tongue in two rows.	9. Horny teeth are present in the buccal funnel and on the tongue.
10. Salivary glands are present.	10. Paired salivary glands are present
11. The gill pouch number varies from six to fifteen pairs.	11. There are seven pairs gill- pouches present. All these open Into the respiratory tube.
12. Each aortic ‘arch supplies the hemibranch of a single gill pouch.	12. Each aortic arch divides and the branches enter the posterior hemibranch of the nearby gill pouch.
13. Brain is degenerated.	13. Brain is well developed.
14. Only thee pairs of cranial nerves are present.	14. Ten pairs of cranial nerves are present
15. Non functional paired eyes are burned in the skin.	15. Paired functional eyes are present.
16. Penial eye is absent.	16. Penial eye is present.
17. In the adult pronephros is retamed. But the functional kidney Is of mesonephric type and simple.	17. The functional adult kidney is mesonephric type.
18. Urinogenital sinus is not seen.	18. Urinogenital sinus is formed.
19. Sexes are united - Hermaphrodite. The anterior part of the gonad acts as ovary & the posterior part act Like Testis.
20. The eggs are large and covered by cylindrical horny shell.	20. The eggs are small and are not covered by horny shell.
21. The development is direct.	21. Development is indirect. Arnmocoetes larva occurs in the life-history.

FEMALE REPRODUCTIVE SYSTEM
RABBIT	FROG
11. Include paired ovaries, oviducts, uteri and singlevestibule, vagina, clitoris and some accessory glands.	11. Include a pair of ovaries, a pair of oviducts and a cloaca.
12. Two ovaries are small, oval, white bodies attached symmetrically and dorsally behind kidneys by mesovarium.	12. Ovaries are a pair of large irregular multilobed, oval,blackish bodies attached near kidneys to dorsal abdominal wall bymesovarium.
13. Two oviducts are large, coiled tubes meeting behindinto vagina, andcalled fallopian tubes. Anterior end of each opens near ovary by a smalloviducal funnel with fimbriated ostium.	13. Oviducts are very long and much coiled glandulartubes opening behind into cloaca. Their anterior ends form separate oviducal funnels with separate openings or ostia, at the bases of lungs.
14. No shell glands present in oviducts.	14. Shell glands are absent.
16. Fallopian tubes are followed by much wider, longer convoluted, vascular and muscular uteri where embryos develop	15. Before entering cloaca, each oviduct expands into a thin-walled ovisac, >. erroneously called uteruswhich is absent.
16. Both uteri meet into a common long, wide and median vagina. It opens with urethra into common urino - genital sinus or vestibule.	16. Vagina absent. So called uteri or ovisacs open directly into cloaca. Vestibule absent.
17. Vestibule opens to outside ventral to anus, through a longitudinal slit like aperture called VULVA.	17. No vulva present. Cloaca opens directly to exterior through a small circular cloacal aperture.
18. Special female sex glands include Cowper's, perineal and rectal glands.	18. No glands.
19. Mammaryglands secrete milk and open on 4 to 5 pairs of ventral teats or nipples in female rabbit. -	19. Absent.

DIFFERENCES BETWEEN EXCRETORY SYSTEM OF RABBIT AND FROG
RABBIT	FROG
1. The kidneys in rabbit are metanephric	1. The kidneys in frog are mesonephric.
2. The kidneys are dark red, bean shaped situated in the middle of the abdominal cavity.	2. Kidneys are flat, dark red structures present towards the posterior end of the body cavity.
3. The right kidney is slightly more anteriorly placed than the left.	3. The right and left kidneys are more or less at the same level.
4. The inner margin of each kidney consists of a notch called hilus.	4. Hilus is absent
5. Ureter emerges from the hilus	5. Ureter emerges from the outer margin of kidney.
6. The ureter expands into a funnel-like pelvis in the kidney.	6. Pelvis is aose~t.
7. The two ureters run posteriorly and open separately into the urinary bladder.	7. The two ureters run posteriorly and open into the cloaca.
8. The ureters carry only urine into the urinary bladder both in male and female.	8. The ureters carry urine and germ cells in males hence they are called urinogenital ducts. While in females they carry only urine.
9. The neck of urinary bladder opens into the urethra that lies in penis. Urethra opens out by an opening at the tip of penis in males. In females it opens into vestibule that inturn opens out by vulva present behind the ciitoris.	9. The neck of urinary bladder opens into the cloaca on the ventral side.
10. The urinary bladder is thin walled, muscular and its neck is called urethra.	10. Urinary bladder is bilobed.
11. The kidney is without bidder's canal	11. The inner margin of kidney consists of bidder's canal to receive spermatozoa and communicate with transverse collecting tubules that open into ureter.
12. The kidneys are supplied with a renal artery and a renal vein. Renal portal vein is absent.	12. The kidneys are supplied with four paris of renal arteries and four pairs of renal veins in addition to a renal portal vein.
13. Uriniferous tubule is divided into i. Proximal convoluted tubule ii. Henle's loop and iii. Distal convoluted tubule.	13. Uriniferous tubule is divided into four parts namely i. Neck like first part ii. Second part, iii. Third part and iv. Fourth part
14. Uriniferous tubule is supplied with capillary network of renal vein	14. Uriniferous tubule is supplied with capillary network of renal portal vein and renal vein.

Rabbit - Venous system	Frog - Venous system
1. Coronary veins collecting the blood from the wall of heart open into left precaval vein.	1. Coronary vein collecting blood from the wall of heart opens into anterior abdominal vein.
2. The blood from different organs of the body is collected by two superior vena cavae and aposterior vena cava which open separately into the right auricle.	2. The blood from different organs of the body is collected by two precavals and one post caval which unite together to form a sinus venosus that inturn opens into right auricle.
3. Each precaval or superior vena cava is formed by three veins namely i. External Jugular ii. Internal jugular and iii. sub-clavian	3. Each precaval vein is formed by three veins viz.i. External jugular ii. Innominate and iii. sub-clavian.
4. External jugular brings blood from tongue, jaws and muscles of the head and is connected with that of the opposite side by a jugular anastomosis	4. External jugular brings the blood from tongue and muscles of jaw by lingual and mandibular.
5. Internal jugular receives internal carotid that receives blood from brain and neck and opens into external jugular vein.	5. Innominate is formed by internal jugular bringing blood from brain and orbit and a sub - scapular from shoulder and back of the arm.
6. The sub-clavian brings blood from shoulders and fore-limbs.	6. The sub-clavian collects blood from forelimbs by brachial vein and from skin and muscles of the abdomen by Musculo-cutaneous vein.
7. Anterior intercostal veins collect blood from intercostal spaces and open into pre - cavals.	7. Anterior intecostal veins are absent.
8. The inferior vena cava is formed by union of several veins.	8. The post caval vein is formed by union of four pairs of renal veins collecting from kidneys.
9. The internal iliacs bring blood from the back of thigh. The external iliac is formed by a femoral vein from the inner part of thigh and a posterior epigastric from ventral wall of abdomen.Vesicular vein brings blood from urinary bladder into internal iliac.	9. Sciatic brings blood from interior of thigh while the femoral brings blood from outer part of the thigh. Vesicular vein from the urinary bladder opens into anterior abdominal vein.
10. Caudal vein collects blood from the tail	10. Caudal vein is absent.
11. Ilio-lumbar from abdomen and gonadial from gonads pour blood into the post caval vein.	11. A dorso lumbar from dorsal body wall pours into renal portal vein while first renal vein also collects from gonad by a gonadial vein.
12. Renal portal system is absent.	12. Renal portal system is well developed.
13. Hepatic portal system is constituted by Hepatic portal vein from different parts of the alimentary canal.	13. Hepatic portal system is constituted by Hepatic portal vein from different parts of alimentary canal and an Anterior abdominalvein from posterior parts of the body.
14. Phrenic veins bring the blood from diaphragm into post caval vein.	14. Phrenic veins are absent.

SIMILARITIES AND DIFFERENCES OF ARTERIAL SYSTEM OF MAMMAL (RABBIT) AND AMPHIBIAN (FROG)
Rabbit - Arterial System	Frog - Arterial System
1. The blood to different parts of the body and lungs is supplied by carotico-systemic trunk and pulmonary aortaoriginating from left ventricle and right ventricle respectively.	1. The blood to different parts of the body and lungs is supplied by three aortic arches (carotid, systemic and pulmocutaneous) oftrucus arteriosusoriginating from right side of the ventricle.
2. The systemic gives a pair of coronary arteries to supply blood to the wall of heart.	2. The blood to the wall of heart is supplied by coronary arteriesoriginating from carotid arches.
3. An innominate artery arises from the carotico systemic arch.	3. Innonimate artery is absent.
4. The innominate artery gives three arteries namely right subclavian, right carotid and left carotid. The left sub-clavian arises from the carotico -systemic directly.	4. The sub-clavians originate from the systemics on either side. Carotid arteriesare the branches of carotid arches on either side.
5. The carotid artery is divided into externaland internal carotid arteries on either side. The external carotid artery supplies blood to the tongue, jaw muscles salivary glands and Internal carotid artery supplies blood to cranium and parts of the brain.	5. The carotid arch is divided into i.Lingual artery to supply blood to the tongue and hyoid muscles and ii. Common carotid artery. The common carotid gives apalatine artery to the roof of buccal cavity and eyes and an Internal carotid-artery to the brain.
6. Each sub-clavian is divided into 3 branches namely L Brachial artery to the fore limbs ii. Vertebral artery - to cavities of vertebrae, spinal cord and parts of brain and iii. Internal mammary artery to supply to thoracic and abdominal muscles.	6. The sub-clavian artery supplies blood to the forelimbs of that side.
7. The caratico-systemic trunk passes asdorsal aorta on the ventral side of vertebral column.	7. The dorsal aorta is formed by rightsystemic only.
8. Paired intercostal arteries from the dorsal aorta supply to the body wall	8. Intercostal arteries are absent.
9. A pair of phrenic arteries supply blood to the diaphragm.	9. Phrenic arteries are absent.
10. The coeliac artery originating from dorsal aorta supplies blood to the liver, spleen, stomach and duodenum.	10. The left systemic after communicating with right systemic separates as coeliaco-mesenteric artery that divides into i.Coeliac and ii. Anterior mesenteric. Coeliac supplies to stomach and liver.
11. The anterior mesenteric artery also originating directly from the dorsal aorta supplies to intestine, pancreas, caecum and colon.	11. The anterior mesenteric supplies to duodenum, ileum, spleen and proceeds as posterior mesenteric.
12. Posterior mesenteric artery supplies blood to colon and rectum.	12. The posterior mesenteric arterysupplies blood to the large intestine.
13. The dorsal aorta gives a pair of renal arteries to kidneys.	13. Four pairs of renal arteries supply blood to the kidneys fromdorsal aorta.
14. Gonadial arteries to the gonads originate directly from the dorsal aorta.	14. Gonadial arteries originate from the first pair of renal arteries.
15. A.pair of lumbar arteries supply blood to the dorsal body wall from dorsal aorta.	15. Lumbar arteries are absent.
16. Caudal artery supplies to the tail	16. Caudal artery is absent.
17. Iliolumbar artery arises from the common iliac and supplies to dorsal body wall. The common iliac divides into i. Internal iliac - to pelvis and ii. External iliac - to the hind limb. * A vesicular arises from common iliac to supply to urinary bladder. The external iliac terminates as femoral artery in the hind limb of that side.	17. Each iliac artery gives rise to i. vesiculo-epigastrictothe urinary bladder and ii.femoral artery to the outer part of thigh. The rest of iliac terminates as sciatic artery to supply to the hind limb.

Rabbit	Frog
1. The heart of rabbit is four chambered with two auricles and two ventricles	1. The heart of frog is three chambered with two auricles and one ventricle.
2. Sinus venosus is absent as it is fused into right auricle	2. Sinus venosus is triangular chamber present on the dorsal side of heart and opens into right auricle.
3. Truncus arteriosus is absent and it is absorbed into the right ventricle	3. Truncus arteriosus is present on the ventral side of heart and it emerges from the right side of ventricle.
4. The right auricle receives blood from different organs of the body by two superior venae cavae (precavals)and one inferior vena cava (post - caval)	4. The blood from different organs of the body is collected by two precavals and one post caval which drain the blood into sinus venosus and then into right auricle.
5. Valves are absent at the opening of precavals into the right auricle. But the opening of posterior vena cava is guarded by Eustachian valve.	5. A pair of sinu-auricular valves guard the opening of sinus venosus into the right auricle.
6. The right auricle and left auricle open into right and left ventricles by auriculo-ventricular apertures which are guarded by tricuspid and bicuspid valves respectively	6. The auriculo - ventricular aperture is guarded by two pairs of auriculo- ventricular valves.
7. A large carotico-systemic trunk arises from the left ventricle and supplies blood to different organs.	7. A large truncus arteriosusoriginates from the right side of ventricle and divides into carotid, systemic and pulmocutaneous arches on either side.
8. A pulmonary aorta originates from right ventricle that supplies deoxygenated blood to the lungs.	8. The deoxygenated blood is carried to the lungs and skin by pulmo-cutaneous arch on either side of truncus arteriosus.
9. Three semilunar valves arepresent at the base of pulmonary aorta and also at the base of carotico systemic trunk.	9. Three semilunar valves arepresent at the base of truncus arteriosus.
10. Any valve is absent in the carotico systemic trunk	10. Truncus arteriosus consists of a longitudinal spiral valve to give mechanical strength to it.
11. Two pace makers namely S.A node and A.V. node are present in the wall of the heart.	11. Only a single pace maker namely S.A node is present on the wall of heart.
12. Bundle of His and purkinje fibres are present for transmission of impulses to the wall of myocardium of ventricles.	12. Bundle of His and purkinje Fibers are absent.

Shark Digestive system		Frog Digestive system
1. The alimentary canal is long and coiled tube divisible into, mouth,buccal buccal cavity, pharynx,oesophagus, stomnch, intestine, rectum and cloeca.		1. Same structures are present.
2. The mouth is ventral, half-moon shaped aperture situated a little behind the anterior end.		2. The mouth is a terminal aperture
3. The upper and lower Jaws are provided with several rows of sharp pointed teeth.		3. The upper jaw alone bears small sharp pointed teeth arranged in a single row. The teeth are absent in the-lower jaw edentulous)
4. The teeth are large and inwardly curved. The teeth can be replaced many times and are polyphyodont.		4. The teeth are minute and downwardly directed. Vomerine teeth also present.
5. The tongue is small, non-muscular and non-retractile, nonglandular. The posterior end is attached to the floor of buccal cavity and the anterior end is free.		5. The tongue is large, highly muscular, retractile and slimy. The anterior end is attached to the floor of the buccal cavity and the posterior end
6. The tongue doesnt help in capturing the food but helps in swallowing the food.		6. The tongue helps in capturing theprey.
7. The side walls of the pharynx areperforated by 5 pairs of gill-slits.		7. The walls of the pharynx are complete.
8. A pair of spiracular openings are also present.		8. Absent.
9. The mucous membrane of the pharynx is rough.		9. The mucous membrane lining the pharynx is smooth and slimy.
10. Glottis is absent.		10. Glottis or the opening oil laryngotracheal chamber is present in the buccal cavity.
11. The stomach is J-shaped and is differentiated into cardiac & pyloric regions.		11 The stomach is not J-shaped but slightly curved sac. it is also differentiated into cardiac & pyloric regions.
12. At the junction of cardiac and pyloric parts there is a smaU blind sac-like outgrowth.		12. No such structure is present.
13. Cardiac valve is present in between the cardiac stomach & pyloric stomach.		13. Absent.
14. At the distal end of the pyloric stomach pyloric valve is present.		14. Pyloric sphincter is present.
15. The pyloric stomach leads into a thick walled muscular chamber-Bursa entiana.		15. Absent.
16. Intestine is comparatively a short tube and it is not differentiated into duodenum and ileum.		16. The intestine is long and coiled tube differented into duodenum (U-shape attain with stomach) andnarrow & long ileum.
17. Intestine possess a spiral valves (Scroll valve)		17. Intestinal wall is produced internally into villi but the scroll valve is absent.
18. The rectal gland opens into the rectum.		18. It is absent.
19. Rectum opens into the cloaca		19. Same.
20. The glands associated with the alimentary canal are liver, pancreas, spleen and rectal gland.		20. The glands associated with the alimentary canal are liver, pancreas and spleen

BRAIN OF CALOTES (GARDEN LIZARD)	BRAIN OF COLUMBA (PIGEON)	BRAIN OF ORYCTOLAGUS (RABBIT)
1. Brain of lizard is relatively small and simple in proportion to the body.	1. Avian brain is much more developed.	1. Mammalian brain is very large and is most advanced in the animal kingdom.
2. Brain is protected by two meninges. They are outer thick duramater and inner thin piamater.	2. Same as in calotes.	2. Brain is protected three meninges. They are outer thick dura mater, inner thin pia mater and archanoid membrane in between the two meninges.
	PROSEN-CEPHALON
3. Olfactory lobes are large diferentiated into an olfactory tract or peduncle and olfactory bulb.	3. The o¥actory lobes are very small and greatly covered by the cerebral hemispheres.	3. Olfactory lobes are more distinctly visible on the ventral side of the cerebral hemispheres.
4. There is no tuber culum of olfactorium. Olfactory lobes are enclosed by olfactory ventricle.	4. There are no tube-rculum of olfactorium and olfactory ventricle	4. Each lobe has olfactory peduncle & olfactory bulb. The peduncle ends behind in a slightly renewed elevation the tuberculum of olfactorium.
5. Cerebral hemispheres are oval with narrow antero posterior ends. These are medially separated by a mid-dorsal fissure.	5. Cerebral hemispheres are very large and form about half of the brain.	5. Cerebral hemispheres are triangular in shape and very large and form about half of the brain.
6. Cerebral hemispheres do not cover olfactory and optic lobes but partly overlap the diencephalon.	6. Cerebral hemispheres largely cover olfactory bbes and diencephalon. These do not overlap optic lobes.	6. Cerebral hemispheres largely cover olfactory lobes diencephalon & optic lobes.
7. There is no corpus callosum.	7. There is no corpus callosum.	7. Cerebral hemispheres are and connected with other by a horizontal transverse band-corpus callosum.
8. Fornix is absent.	8. Fornix is absent.	8. Posterior end of corpus callosum bends down and extends forward as fornix.
9. The surface of cerebral hemispheres is smooth and are not differentiated, into lobes.	9. The surface of cerebral hemispheres is smooth and are not differentiated into lobes.	9. Each cerebral hemisphere is differentiated into four lobes - Frontal, parietal, Temporal & Hippo campal.
10. Cerebral cortex is not well developed.	10. Same as in calotes.	10. Cerebral cortex is well developed.
11. Corpora striata are quite conspicuous.	11. Corpora striata are very conspicuous.	11. Corpora striata are less conspicuous
12. Lateral ventricles are unbranched.	12. Same as in calotes.	12. Lateral ventricles are branched.
13. Diencephalon is a small rounded area pressed between the cerebrum and midbrain.	13. Diencephalon is visible on the ventral side and dorsally cov-ered by cerebral hemispheres.	13. Diencephalon is comparatively small and -completely covered with backward extension of cerebral hemispheres.
14. Diencephelon roof is thin and forms anterior choroid plexus.	14. Same as in calotes.	14. The roof of dienceph-alon is thin and highly vascular and forms the anterior choroid plexus.
15. Epiphysial apparatus possess an anterior parietal body and posterior penial body.	15. Epiphysial apparatus possess pineal body as.	15. Same as in columba.
16. Optic thalami are present but middle commissure is lacking.	16. Opticthalamiare well developed but there is no middle commissure.	16. Opticthalami are connected together by a thick band of grey matter called as middle commissure.
17. Pineal eye is present.	17. Absent.	17. Absent.
18. Corpus albicans is absent.	18. Absent.	18. Asmall, rounded body, the corpus albicans or corpus mamillare present behind pituitary body.
	MESEN-CEPHALON
19. Two optic lobes are oval and are present dorsally to form corpora bigemina	19. Two optic are large and present laterally to form corpora bigemina.	19. Optic lobes are small and four in number and form as corpora quadri gemina which are covered by cerebellum.
20. The crura cerebri at the floor of midbrain are poorly developed.	20. Crura cerebri are well developed.	20. Crura cerebri are highly developed.
21. Optic lobes are hollow with optocoels.	21. Optocoels are much reduced.	21. Optic lobes are solid and without optocoels.
	RHOMBEN-CEPHALON
22. Cerebellum is poorly developed and it is in the form of a flattened ridge at the anterior end of medulla oblongata.	22. Cerebellum is comparatively more developed and divided into two lateral and a median lobe.	22. Cerebellum is very well developed and divided into two lateral lobes and a median lobe.
23. Cerebellum surface is smooth.	23. Cerebellum surface is folded all over.	23. Same as in bird.
24. Cerebellum is not differentiated into lobes.	24. Cerebellum is differentiated into three lobes - a median large, oval central lobe or vermis and pair of very small lateral floccular lobes.	24. Cerebellum is differentiated into five lobes - a median large central lobe or vermis, a pair of smaller lateral lobes and a pair of still smaller floccular lobes.
25. Pons varolii are absent.	25. Same as in calotes.	25. Pons varolii are present and connect the lateral parts of the cerebellum.
26. There is no arbor vitae.	26. Same as in calotes.	26, White matter forms tree-like arbor vitae in grey matter can be seen in the section of cerebellum.
27. Medulla oblongata is not overlapped by the cerebellum.	27. Medulla oblongata is overhung by cerebellum.	27. Same as in cloumba.
28. It has a distinct ventral flexure.	28. Same as in calotes.	28. Ventral flexure is absent.
29. Ventral fissure and ventral pyramids are absent.	29. Same as in calotes.	29. There is a median ventral fissure bordered by two narrow bands - the ventral pyramids.
30. Corpora trapezo-idea are not formed.	30. Corporatrapezoidea are lacking.	30. A pair of oblong patches - corpora trape-zoidea are present just behind pons varolii.
31. The roof of medulla is thin and vascular which forms the posterior choroid plexus	31. The posterior choroid plexus is completely covered with the cerebellum.	31. The roof of medulla is exceptionally thin and forms the posterior choroid plexus.
32. Velum medullae anterius is not formed.	32. Velum medullae i; absent.	32. A thin transparent membrane - Velum medullae anterius forms the roof over the anterior part of the fourth ventricle. This connects the optic lobes with the cerebellum.
33. Velum medullae posterius is absent.	33. Same as in calotes	33. A thin transparent membrane - Velum medullae posterius forms the roof over hind part of the fourth ventricle.

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Shark Digestive system

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