DIGESTIVE SYSTEM. 163 



more thinly walled cavity that rests upon it. A similar double form of 

 stomach occurs also in other Reptiles, as in Trigonocephalus and Acro- 

 chordus javanicus among the Serpents, in whom both the sacs are 

 separated by a valve. A pyloric constriction is nearly always pres- 

 ent, but is absent in several genera out of all the orders. The 

 intestine often exceedingly short, as in Pipa, where there is no 

 trace of a division into particular portions, makes nevertheless in 

 most cases some convolutions, and is divided into small and large 

 intestine, the limits of the latter being denned by means of a ccecum 

 coli. The intestinal canal is longest in the vegetable feeding Che- 

 Ionia, although it does not exceed the length of the body more than 

 twice, and next to them, in the Crocodiles. 



The CoRcum Coli varies very much, being absent in the naked 

 Amphibia, and most Serpents, though it occurs among the latter in 

 Tortrix and Python ; among the Chelonia, Testudo is provided with 

 a short but wide co3cum ; it is very small in Lacerta, somewhat 

 larger in Scincus. Other Sauria, as the Crocodiles, have no coBcum 

 whatever. 



The alimentary canal terminates by opening into the cloaca, and 

 is usually provided with longitudinal folds or cells, the forms of which 

 either vary greatly, or pass gradually into each other. 



The Salivary glands are exhibited under very different degrees 

 of development, and are actually wanting in most genera, as en- 

 tirely in the aquatic Ichthyodea, Batrachia, and the marine Che- 

 Ionia. Even in the Crocodiles, and many other Sauria, they are 

 either absent entirely, or only very slightly developed. They occur, 

 on the contrary, very generally among the Ophidia. The Serpents 

 have in addition to a gland, that is occasionally developed to a great 

 extent at the base of the tongue and within the oral cavity, a pair 

 of considerably elongated glands, which cover the jaws. One of 

 these, called the supra-maxillary or labial gland, lies along the bor- 

 der of the upper jaw, and is very conspicuous in the Vipers, less 

 developed in the large Serpents, and nearly obliterated altogether 

 in the true Venomous kinds, although it is still to be seen distinctly 

 in Homalopsis and Trigonocephalus. The other, the inferior max- 

 illary or labial gland, is situated upon the external side of the lower 

 jaw, and is tolerably distinct, even in the true Venomous Serpents. 

 The poison gland can not be included among the salivary glands, but 

 is to be viewed as a special organ of secretion. 



The Liver of the Reptiles is of large size, either very elongated 

 and undivided, as in the Serpents and Ichthyodea, or broader, as in 



