DEVELOPMENT OF ELASMOBRANCH FISHES. 253 



tremltles of the oviducts, with their abdominal openings, are to 

 be found in the male in the same position as in the female, on 

 the front surface of the liver. 



In the female the same ducts are present as in the male, 

 viz. the Wolffian duct and the ureters. The part of the 

 Wolffian duct which receives the secretion of the Wolffian 

 body is not contorted, but is otherwise similar to the homo- 

 logous part of the Wolffian duct in the male. The Wolffian 

 ducts of the two sides fall independently into an unpaired uri- 

 nal cloaca, but their lower ends, instead of remaining simple 

 as in the male, become dilated into urinary bladders. Vide 

 PI. XIX. fig. 2. There were nine ureters in the example dis- 

 sected, whose arrangement did not differ gTeatly from that 

 in the male — the hinder ones remaining distinct from each 

 other, but a certain amount of fusion, the extent of which 

 could not be quite certainly ascertained, taking place be- 

 tween the anterior ones. The arrangement of the openings 

 of these ducts is not quite the same as in the male. A some- 

 what magnified representation of it is given in PL xix. fig. 3, 

 0. u. The two Wolffian ducts meet at so acute an angle that 

 their hindermost extremities are only separated by a septum. 

 In the region of this septum on the inner walls of the two 

 Wolffian ducts were situated the openings of the ureters, of 

 which there were five on each side arranged linearly. In a 

 second example, also adult, I found four distinct openings on 

 each side similarly arranged to those in the specimen described. 

 Professor Semper states that all the ureters in the female unite 

 into a single duct before opening into the Wolffian duct. It 

 will certainly surprise me to find such great variations in 

 different individuals of this species as is implied by the dis- 

 crepancy between Professor Semper's description and my own. 



The main difference between the ureters in the male and 

 female consists in their falling into the urinogenital cloaca in 

 the former and into the Wolffian duct in the latter. Since, 

 however, the urinogenital cloaca is a derivative of the Wolffian 

 duct, this difference between the two sexes is not a very im- 

 portant one. The urinary cloaca opens, in the female, into the 

 general cloaca by a median papilla of somewdiat smaller di- 

 mensions than the corresponding: papilla in the male. Seminal 



