REPTILIA. 585 



being firmly imbedded in the sacral region. But in the Serpents, in 

 consequence of the elongated form of the body, and the complete 

 flexibility of every portion of the spine, the kidneys are peculiar 

 both in their position and general structure. Instead of being 

 placed upon the same level as in other Vertebrata, the right kidney 

 of an Ophidian is situated much more anteriorly than the left ; a 

 circumstance which much facilitates the packing of the abdominal 

 viscera, and contributes greatly to ensure the free movements of 

 the vertebral column at this place. For the same reason, the 

 kidneys of a serpent are divided into numerous lobes, placed in a 

 longitudinal series upon the outer side of the commencement of the 

 ureter, and loosely connected to each other and to the spine by 

 cellular tissue and a fold of the peritoneum. 



As relates to the minute structure of the kidneys in the Rep- 

 tilia, these viscera are invariably composed of convoluted tubes, 

 which pour their secretion into the commencement of the cor- 

 responding ureter. The ureters of course vary in length accord- 

 ing to the position of the renal organs ; they ultimately terminate 

 in the cloaca (Jig. 267, u) ; a cavity or general outlet through 

 which, in the female, the ova, the fseces, and the urine are dis- 

 charged, and which in the male gives passage to the contents of 

 the rectum, the secretion of the kidneys, and the semen. 



(647.) In connection with the urinary apparatus of Reptiles, it 

 will be convenient to mention a bladder that exists in Chelonian 

 and Amphibious Reptiles, and is also found in some Saurian tribes, 

 to which the name " urinary bladder"" has been erroneously applied. 

 This bladder, in the Tortoise (Jig. 267, A) and Proteus (Jig. 

 254, q) is of considerable size, and in the Frog forms a very capa- 

 cious receptacle, having its upper part divided into two cornua. 

 It is generally filled with a clear limpid fluid, which in the case of 

 the Frog is forcibly ejected if the animal be alarmed : but that this 

 fluid is not urine is obvious from the fact already stated, that the 

 ureters open into the cloaca (Jig. 267, u), and not into the bag 

 referred to ; the latter, in fact, is the unobliterated remains of the 

 ALLANTOIS of the embryo, concerning which further particulars 

 will be given in the next chapter, and the fluid contained in it is 

 most probably the product of cutaneous absorption.* 



(648.) In tracing the developement of the generative apparatus 



* Vide Cyclopaedia of Anatomy and Physic, art. AMPHIBIA, by Professor Bell, 

 p. 104. 



