248 SNAKES, TURTLES, LIZARDS, CROCODILES 



Scales. — The whole body is covered with scales which are 

 true epidermal structures. The scales on the dorsal side 

 of the head are large and shieldlike. Those on the dorsal 

 side of the abdomen are small and hexagonal, while those 

 on the ventral surface are large, rectangular m shape, and 

 arranged in eight longitudinal rows. The scales on the 

 tail are keeled and arranged in regular transverse rows 

 which give a ringed appearance to this organ. 



The digestive system. — The mouth opens into a slender 

 gullet which leads to the stomach. Following the stomach 



Glottis 



Qvidticl 



Kidnei/ 



<lJreter 



\Cloaca 



^cMiladder 



Fig. 171 . — Internal structure of a Hzard. 



Urinary 

 bladder 



is the small intestine, or duodenum, which is more or less 

 coiled. The duodenum is succeeded by the large intestine, 

 or rectum, which joins the cloaca, the dilated end of the aU- 

 mentary canal. A two-lobed Uver Ues in the anterior part 

 of the body cavity and has a gall bladder which empties 

 into the duodenum through the bile duct. A pancreas is 

 situated in the loop between the duodenum and stomach. 

 At the point of union between the small and large intestine, 

 the latter is produced into a short, blind sac, the ccecum 

 (Fig. 171). 



