448 



MANUAL OF ZOOLOGY 



of the Crocodilia, the presence of a rudimentary csecum at 

 the junction of small and large intestines in most Lacertilia 

 and in the Ophidia, and the presence of numerous large 

 cornified papillae in the oesophagus of the Turtles. 



The Reptiles have all an 

 elongated trachea, the wall 

 of which is supported 

 by numerous cartilaginous 

 rings. The anterior part 

 of this is dilated to form the 

 larynx, the wall of which 

 is supported by certain spe- 

 cial cartilages — the cricoid 

 and the arytenoids. The 

 trachea bifurcates posteri- 

 orly to form two bronchi, 

 right and left, one passing 

 to each lung. 



The lungs of the Lacer- 

 tilia and Ophidia are sim- 

 ple and sac-like, like those 

 of the frog. In the Croco- 

 dilia and Chelonia they are 

 of a more complex char- 

 acter, being divided inter- 

 nally by septa into a number 

 of chambers. 



In the heart (Fig. 269) 

 the sinus venosus is always 

 distinct, and is divided into 

 two parts by a septum ; 

 its aperture of communication with the right auricle is 

 guarded by valves. There are always two quite distinct 



Fig. 269. — Heart of monitor (Varanus) 

 dissected to show the cavity of the 

 ventricle and the vessels leading out 

 from it. A. A', auricles; Ao, dorsal 

 aorta; Ap. Afi' , pulmonary arteries; 

 Asc, subclavian artery; Ca. Ca', caro- 

 tids; RA. RA, roots of dorsal aorta; 

 Trca, innominate trunk; V, ventricle; 

 t, right aortic arch; *, left aortic arch. 

 (From Wiedersheim.) 



