632 EXCRETING ORGANS. 



appearance. Their distance from the cloaca increases, the 

 ureters elongate, especially that of the right side, a lobulated 

 or convoluted surface is developed, the ureters open into 

 the cloaca, close to the ducts of the deciduous kidneys or 

 corpora Wolffiana. 



In the saurian reptiles there is more generally a urinary 

 bladder, and the kidneys are less elongated, and situated 

 farther backwards in the pelvic region of the trunk, than in 

 ophidia. In the crocodiles, however, and some others, 

 where there is no urinary bladder, the ureters open sepa- 

 rately into the dorsal part of the cloaca, as in bird^ and many 

 inferior vertebrata. And even where there is a urinary 

 bladder in the sauria, the ureters do not open directly into 

 its cavity or fundus, as they do in most mammalia, but into 

 the dorsal part of the cloaca near the neck of the bladder, 

 as is seen likewise in fishes amphibia and chelonia. The great 

 size of the urinary bladder in these animals results from its 

 containing the entire allantois, which is not protruded from 

 an external umbilicus, nor constricted and obliterated to 

 form a urachus as in mammalia. The kidneys of the cro- 

 codilian sauria are surrounded with tortuous superficial folds, 

 and appear more deeply lobulated externally, like those of 

 serpents, and from the ureters sending off numerous lateral 

 ducts, they are more complicated in the internal arrange- 

 ment of their tubuli, than in the lizards. Their tubuli 

 uriniferi, however, do not form tortuous groups arising from 

 short wide primary ducts, in each of the several lobes, as in 

 serpents, but diverge regularly in straight radiating lines 

 from around a central wide duct, which traverses the whole 

 extent of the axis of each lobe ; so that a vertical section of 

 a part of one of the lobes presents a pinnate appearance, with 

 parallel straight tubuli extending to the periphery from the 

 central duct. The kidneys are more developed at their 

 anterior part in some of the lizards, as they are in birds, and 

 taper backwards to their posterior ends, being shorter in 

 sauria than in ophidia, and longer than in chelonian reptiles. 

 In the embryo, the kidneys are more elongated, as in ser- 

 pents, and their short simple tubuli extend directly from 

 the side of the ureter, without indication of the lobulated 

 structure seen in the adult Jacertee, 



The kidneys of chelonian reptiles have a more concen- 



