488 DEVELOPMENT OF ELASMOBRANCH FISHES. 



Professor Semper states that there is but a single vas efferens in 

 Scyllium canicula, a statement which appears to me unquestion- 

 ably erroneous. All the vasa efferentia fall into a longitudinal 

 duct (I. c), which is connected in succession with the several 

 segments of the Wolffian body (one for each vas efferens) which 

 appertain to the testis. The hind end of the longitudinal duct 

 is simple, and ends blindly close to its junction with the last vas 

 efferens ; but in front, where the vasa efferentia are complicated, 

 the longitudinal duct also has a complicated constitution, and 

 forms a network rather than a simple tube. It typically sends 

 off a duct to join the coils of the Wolffian body between each 

 pair of vasa efferentia, and is usually swollen where this duct 

 parts from it. A duct similar to this has been described by 

 Semper as Nierenrandcanal in several Elasmobranchs, but its 

 existence is expressly denied in the case of Scyllium ! It is 

 usually found in Amphibia, as we know from Bidder and Spengel's 

 researches. Spengel calls it Langscanal des Hoden ; the vessels 

 from it into the kidney he calls vasa efferentia, and the vessels to 

 it, which I speak of as vasa efferentia, he calls Quercanale. 



The exact mode of junction of the separate vasa efferentia 

 with the testis is difficult to make out on account of the opacity 

 of the basal portion of the testis. My figure shews that there 

 is a network of tubes (formed of four main tubes connected 

 by transverse branches) which is a continuation of the anterior 

 vasa efferentia, and joined by the two posterior ones. These 

 tubes receive the tubuli coming from the testicular ampullae. 

 The whole network may be called, with Semper, the testicular 

 network. While its general relations are represented in my 

 figure, the opacity of the testes was too great to allow of all 

 the details being with certainty filled in. 



The kidneys of Scyllium stellare, as might be expected, 

 closely resemble those of Scy. canicula. The ducts of the kidney 

 proper, have, in the former species, a larger number of distinct 

 openings into the urinogenital cloaca. In two male examples 

 I counted seven distinct ureters, though it is not impossible 

 that there may have been one or two more present. In one 

 of my examples the ureters had seven distinct openings into the 

 cloaca, in the other five openings. In a female I counted eleven 

 ureters opening into the Wolffian duct by seven distinct openings 



