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 nares 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 (Esophagus. The stomach opens 

 by a pyloric valve into the small intes- 

 tine; this is separated from the large 

 intestine by the ileoccecal 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 

 septum. 

 body is carried by the postcaval vein d ' right auricle; d.ao dorsal 



aorta; pd, right; ps, left pul- 

 and the two precaval veins into the mbnary artery; s, left auricle; 



sinus venosus and thence into the 



d.ao 



FIG. 441. Heart and ar- 



by a perforated teries of a turtle > 



1 - ad, right; as, left aortic arch; 



The venOUS blood from the f , carotid; c', cceliac artery; 



sj < rl ^> . left subclavian 



artery. (From bedgwick s 



right auricle (a). 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 1 ) 

 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 (5) and thence into the left 



