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 Eust,achian 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 ileocacal 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 FIG. 441. Heart and ar- 

 divided into two by a perforated terie * of a turtle > Chelydra. 



ad, right; as, left aortic arch; 

 Septum. The venous blood from the c , carotid; c', coeliac artery; 



body is carried by the postcaval vein d > r 'g ht auricle; d.ao dorsal 



J aorta; pd, right; ps, left pul- 



and the two precaval veins into the monary artery; 5, left auricle; 



sinus venosus and thence into the sd > ri e ht ; " left subdavian 



. 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 f ) 

 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 



d.ao 



