330 



COLLEGE ZOOLOGY 



exposed (Fig. 212). The heart hes within 

 the sadike pericardium; it is partially sur- 

 rounded by the three lobes of the reddish- 

 brown liver. The two lungs lie, one on either 

 side, near the anterior end of the abdominal 

 cavity. Coiled about within the body cavity 

 are the stomach and intestine. The kidneys 

 are flat reddish bodies attached to the dorsal 

 body wall; they lie outside the coelom, just 

 behind a thin membrane, the peritoneum. 

 The two testes of the male are small ovoid 



organs suspended by membranes and lying 

 at the sides of the digestive tract. The 

 ovaries and oviducts of the female occupy 

 a large part of the body cavity during the 

 breeding season. The coelom is lined with a 

 membrane of mesodermal origin, the 

 peritoneum. The reproductive organs and 

 digestive tract are suspended by double 

 layers of peritoneum called mesenteries 

 (Fig. 213). 

 In man, a diaphragm separates the tho- 



Tongue 



Opening of 



Eustachian 



tube 



Right atrium 

 Left atrium 

 Ventricle 

 Sinus venosus 



Liver 

 Stomach 



Gall bladder 

 Coeliacomesen- 

 teric artery 



Hepatic 

 portal vein 



Pancreas 

 Coelom - 

 Small intestine 



Ventra 

 abdommal vein 



Large intestine 

 Bladder 



^>^^ External nares 



^^^^ Internal nares 



Mouth cavity 



Brain 



Opening of 



vocal sac 



Pharynx 

 Glottis 



Esophagus 

 Systemic arch 



Lung 

 Nerve cord 



Posterior 

 vena cava 



Fe 



moral vein' 



Dorsal aorta 



Kidney 

 Fat body 



Testis 



Adrenal 



gland 



Spleen 



Vertebra 



Urostyie 



Urinary ducf 



Renal portal vein 

 Iliac artery 



Cloaca 



Cloacal 

 opening 



Figure 212. Internal structure of a frog. 



