248 



SNAKES, TURTLP:S, 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 lai'ge and shieldUke. Those on the dorsal 

 side of the abdomen are small and hexagonal, while those 

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

 arrangetl in eight longitudinal rows. The scales on the 

 tail are keeled and arranged in regular tran.sverse 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 



Hi. 



Oviduct 

 Ovar // r2;;;;::^:^idney 



__^ ^^ JJrrter 



Rectum 

 Gallbladder 



Urinary 

 bldiider 



Fir; 171 . — JiitiTual structure of a lizard. 



is the small intestine, or dunden inn , which is more or less 

 coiled. The duodenum is succeeded by the large intestine, 

 or redinri, which joins tlie cloaca, the dilated end of the ali- 

 mentaiy canal. A two-lobed liver lies in the anterior part 

 of the l)ody cavity and has a gall bladder which empties 

 into the (hiodenum (lirough the bile duct. A pancreas is 

 situated in the loop l^etween 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 ccccum 

 (Fig. 171). 



