536 



ANATOMY OF VERTEBRATES. 



354 



oval or pyriform, often bifid at its fundus, or two-horned ; it is 

 largest in those fishes, as the Pleuronectida, Lophius, Orthagoriscus, 

 and Cyclopterus, in which the air-bladder is absent. In Catty ony- 

 mus the bifid urinary bladder extends the whole length of the 

 abdomen. It always lies behind the rectum, generally receives 

 the ureter or ureters nearer its fundus than its cervix, and the latter 

 is prolonged usually into a prominent papilla behind the vent. 

 The lono- cervix vesicoe in the Salmon is surrounded by a venous 



plexus. In the Sturgeon the wide 

 ureters extend along the outer 

 borders of the kidneys, and re- 

 ceive the vasa defer entia or the 

 oviducts in their course towards 

 the cloaca, where they unite into 

 a short duct which forms the com- 

 mon outlet of the urinary and 

 generative products. 



The kidneys are long, narrow, 

 but distinct from each other in 

 all the Ganoid Fishes and in the 

 Lepidosiren. In the Lophius the 

 kidneys present a more compact 

 form, and are situated wide apart, 

 far forwards in the abdomen, in 

 depressions on either side of the 

 origins of the ' retractores palati.' 

 The kidneys of the Plagiostomes 

 are also of a more compact form 

 than in Osseous Fishes, and are 

 always distinct, and generally 

 show a cerebriform convoluted or 

 lobulated exterior : the primary 

 branches of the uriniferous tubes are fewer, and their dichotomous 

 ramifications more numerous i 1 the ureteric trunk becomes superficial 

 along the inner and fore-part of the hinder half of each kidney ; 

 after quitting which it dilates in the Grey Shark (^Galeus) into a 

 kind of receptacle, fig. 352, m, behind each oviduct or vas deferens, 

 and communicating with its fellow near the cloaca, terminates by 

 a single urethral canal upon a kind of penis or clitoris, ib. o, 

 at the back of the anus, within a large common cloaca. In the 

 Torpedo, the ureters terminate on the cloacal papilla by two dis- 



1 In the Ray, the diameter of the terminal branches of the tubuli uriniferi are 

 of an inch, that of the capillary renal arteries being y^th of an inch. 



Cj 



Kidney and generative organs, Lamprey (Pctro- 

 myzon mariutts). xx. 



