REPTILIA. 



295 



The stomach is closely connected with 

 the liver, and in some species, as, for ex- 



Fig. 215. 



Draco volans. 



a, ventricle of the heart ; b, the right auricle ; c, 

 the left auricle ; d d, carotid arteries ; e e, the vena 

 j ugularis ; Jf, the subclavian artery ; g, the trachea ; 

 h, the right lung ; i, the left lung ; k, the liver ; 1 1, 

 the lower venous sinus, which commences from the 

 liver and extends to the right venous sinus ; m, the 

 biliary duct ; o, the stomach ; p, the commence- 

 ment of the small intestine; qqq, the windings of 

 the small intestine ; r, the commencement of the 

 large intestine; s, its attenuated region; tt, the 

 kidneys; u, the cloaca; v, the bladder; w, the 

 anus. 



ample, in Emys concina, absolutely imbedded 

 in its substance. 



The diameter of the small intestine in the 

 Chchnians gradually diminishes from the py- 

 lorus to its termination in the large intestine, 

 the diameter of which is much larger, and its 

 extremities much thicker. The parietes of 

 the whole intestinal canal are indeed thicker 

 than in most other reptiles. The calibre of 

 the intestine is uniform throughout, and its 

 lining membrane presents folds of variable 

 breadths in different species, which are gene- 

 rally united together so as to form a kind of 

 net-work at the commencement of the small 

 intestine, but subsequently these become 

 longitudinal and parallel. In the large in- 

 testines these folds become less regular in 

 their arrangement. 



It may be added to the above general de- 

 scription, that the alimentary canal of the 



reptiles belonging to this order presents differ- 

 ences in each genus, and even in some species 

 of the same genus, which are in relation with 

 corresponding differences in the nature of 

 their food. The tortoises and the turtles, 

 which live principally upon herbs or fuci, 

 have the intestinal canal long ; the large in- 

 testine longer than the small ; the latter being 

 inserted into the former laterally, so as to 

 leave a small cascum behind the point of 

 entrance. 



In the different species of Emydes, which 

 are more carnivorous in their habits, and in 

 the Trionyx, the alimentary canal is shorter 

 at least the large intestine, which is not 

 longer than the small; and the latter is 

 continuous with the large intestine, without 

 there being any insertion of one into the 

 other. 



The Crocodilidce differ from all other saurian 

 reptiles in the form of their oesophagus and 

 stomach. 



The oesophagus is a narrow canal, easily 

 distinguishable Irom the stomach on account 

 of the globular form of the latter, and also by 

 the different structure of mucous and cellular 

 coats, the former of which is plicated and 

 villous in the oesophagus, while the latter is 

 very thin, and hardly perceptible. 



The stomach is a great rounded globular 

 cul-de-sac (fig. 2 13.), into which the oesophagus 

 opens, at no great distance from the pylorus. 

 Close to this insertion there is, inferiorly, a 

 small cul-de-sac (g), the cavity of which is se- 

 parated from the larger cul-de-sac by a narrow 

 passage, and which opens into the intestine 

 by a constricted orifice. Necessarily, ali- 

 mentary substances must pass through this 

 channel into the pyloric cul-de-sac, in order 

 to escape from the stomach. This structure 

 evidently corresponds to the pyloric portion 

 of the stomach in ophidian reptiles, to be 

 described hereafter. 



Generally, the parietes of the stomach are 

 very strong; the mucous lining is smooth, 

 thick, and very glandular, forming here and 

 there broad folds, which run in a serpentine 

 manner, like the convolutions of the brain. 

 The cellular tunic, which was not very dis- 

 tinct in the oesophagus, becomes so in the 

 stomach, whilst the muscular coat almost 

 equals in thickness that of the cellular and 

 mucous tunics combined : it is principally 

 composed of fasciculi, which radiate from the 

 centre towards the circumference, arising 

 from an aponeurotic disc, which exists on 

 both the abdominal and dorsal aspects of the 

 organ. This stomach very nearly resembles 

 the gizzard of a bird ; and the resemblance 

 becomes more striking if it be compared with 

 the gizzard of a heron, the walls of which 

 are thin, and which also opens into a little 

 appendage. 



The small intestine in the Nilotic crocodile 

 may be distinguished into two portions : the 

 first of these is wide, with thin walls, and is 

 bent four times upon itself, so as to make 

 four permanent folds : this portion is equal 

 in length to about four-tenths of the whole 



17 4 



