562 



REPT1LIA. 



tlier among the innumerable instances that might be adduced of 

 that gradual transition everywhere observable as we pass from one 

 class of animals to Fig. 253. 



that which next suc- 

 ceeds it in the series 

 of creation. The 

 Crocodile is the con- 

 necting link be- 

 tween REPTILES 

 and BIRDS, and in 

 almost every part of 

 its body it presents 

 a type of structure 

 almost intermediate 

 between the two. 



The stomach of 

 this creature (Jig. 

 253) might in fact 

 be almost mistaken 

 for the gizzard of a 

 rapacious bird. The 

 oesophagus (c) terminates in a globular receptacle, the walls of 

 which are very muscular, and the muscular fibres (a) radiate from a 

 central tendon (b) precisely in the same manner as those of a bird. 

 The pyloric orifice is closely approximated to the termination of 

 the oesophagus, and the commencement of the duodenum dilated 

 into a round cavity (d) ; an arrangement which, as we shall see in 

 the next chapter, exactly resembles that met with in the feathered 

 tribes. 



In the neighbourhood of the pylorus, the walls of the stomach in 

 all the REPTILIA become perceptibly thickened : the intestine is 

 generally short and usually divided into two portions, representing 

 the small intestines and the colon, the division between the two 

 being marked by a prominent valve analogous in function and posi- 

 tion to the ileo-colic valve in the human subject ; and sometimes, 

 moreover, as, for instance, in the Iguana, there is a distinct ceecum 

 developed at the commencement of the large intestine. 



The auxiliary secretions subservient to digestion in the class 

 before us, are the Salivary, the Hepatic, and the Pancreatic. 



(620.) The Salivary glands are of very peculiar construction.* 



* Cuvier, Le9ons d'Anatomie Compare, torn. iii. p. 223. 



