CLASS REPTILIA 



531 



The digestive organs are simple. The broad, soft tongue is 

 attached to the floor of the mouth cavity; it is not protrusible. 

 The two posterior hares are situated in the anterior part of the 

 roof of the mouth. At the base of the tongue is a longitudinal 

 slit, the glottis, and a short distance back of the angle of the 

 jaw are the openings of the Eustachian tubes. The pharynx 

 is thin-walled and very distensible; it 

 leads into the more slender and thicker- 

 walled oesophagus. The stomach opens 

 by a pyloric valve into the small intes- 

 tine; this is separated from the large pd 

 intestine by the ileocecal valve. The 

 terminal portion of the alimentary 

 canal is the rectum ; it opens into the 

 cloaca. There is no intestinal caecum. 



The liver discharges bile into the in- 

 testine through the bile-duct. Several 

 pancreatic ducts lead from the pan- 

 creas to the intestine. 



The Circulatory System. — The 

 heart (Fig. 441) consists of two auricles 

 (d, s), and a single ventricle which is 

 divided into two by a perforated 

 septum. The venous blood from the 

 body is carried by the postcaval vein 

 and the two precaval veins into the 

 sinus venosus and thence into the 



artery. (From Sedgwick s 



right auricle (d). From here it passes Zoology, after Gegenbaur.) 

 into the right side of the ventricle, 



and, when the latter contracts, is forced out through the pul- 

 monary artery, which sends a branch {pd, ps) to each lung, and 

 through the left aorta (as) which conveys blood to the viscera (c') 

 and into the dorsal aorta (d.ao). 



The blood which is purified in the lungs is returned by the 

 pulmonary veins to the left auricle (s) and thence into the left 



Fig. 441. — Heart and ar- 

 teries of a turtle, Chelydra. 

 ad, right; as, left aortic arch; 



c, carotid; c', cceliac artery; 



d, right auricle; d.ao, dorsal 

 aorta; pd, right; ps, left pul- 

 monary artery; 5, left auricle; 

 sd, right; 55, left subclavian 



