294 



REPTILIA. 



breath with facility whilst only the tip of its 

 Fig. 213. 



Throat, (Esophagus, and Stomach of the Crocodile. 



a, nostrils ; I, postorbital plate ; c, tongue ; d, 

 valves of the fauces ; e, oesophagus ; /, muscular 

 portion of stomach ; i, central tendons of ditto ; 

 g k, commencement of duodenum. 



nose is above the surface of the water, (fig. 

 213.) 



Digestive System. The oesophagus of rep- 

 tiles is never dilated into a crop, as in birds ; 

 it either preserves nearly the same diameter 

 throughout its entire length, or, if its capacity 



varies, it is insensible, and not by any sudden 

 dilatation. But its diameter is generally- 

 much greater relative to the stomach, than in 

 Mammalia or birds. In the Ophidians it is 

 even more capacious than the stomach, at 

 least when the latter is not distended with 

 food : this happens because the walls of the 

 stomach are more muscular than those of 

 the oesophagus, and, consequently, contract 

 more forcibly. When the oesophagus gra- 

 dually dilates as it approaches the stomach, it 

 often becomes difficult to say where one termi- 

 nates and the other begins, and, consequently, 

 to assign the situation of the cardia. The 

 stomach is generally without any cul-de-sac, 

 and its form much elongated. Most reptiles 

 living upon prey have the digestive apparatus, 

 and more particularly the stomach, of carni- 

 vorous animals. The latter viscus is always 

 single, never multiple ; its cavity being simple, 

 never complicated. Even in those reptiles 

 that feed on vegetable substances, the same 

 plan of organization is retained, very slightly 

 modified by such opposite habits. 



The oesophagus of some Chelonian reptiles 



Fie. 2 14-. 



Horny Processes in (Esophagus of Turtle. 



presents internally its whole inner surface 

 crowded with long, hard, conical papilla? 

 (Jig. 214-.), the points of which are directed 

 backwards towards the stomach, and doubt- 

 less serve to prevent the return of substances 

 swallowed towards the mouth. The muscular 

 coat is generally very strong. 



The stomach is generally of an elongated 

 form and cylindrical shape ; its longest por- 

 tion is directed backwards ; it then suddenly 

 bends at an angle, and runs forwards. The 

 second portion, which terminates at the py- 

 lorus, is always shorter than the first ; its 

 muscular coat is thicker than in the cardiac 

 portion, and its lining membrane here forms 

 longitudinal folds, which are more numerous 

 and distinct. The pylorus is indicated by a 

 circular elevated ring, which is sometimes 

 very thick, or else by a fold. 



Generally the walls of the stomach in the 

 Chelonian reptiles are thick, partly owing to 

 the strength of the muscular tunic, partly to the 

 thickness of the mucous and cellular coats, the 

 latter being penetrated by numerous crypts. 



