DEVELOPMENT OF ELASMOBRANCH FISHES. 251 



Wolffian bodies extend somewhat further forwards than in the 

 female. Leaving the finer details of the glands for subsequent 

 treatment, I pass at once to their ducts. These differ slightly 

 in the two sexes, so that it will be more convenient to take 

 the male and female separately. 



A partly diagrammatic representation of the kidney and 

 Wolffian body of the male is given on PL xix. fig. 1. The secre- 

 tion of the Wolffian body is carried off by a duct, the Wolffian 

 duct [w.d.), which lies on the ventral surface of the gland, 

 and receives a separate ductule from each segment (PL xix. 

 fig. 5). The main function of the Wolffian duct in the male is, 

 however, that of a vas deferens. The testicular products are 

 brought to it through the coils of the anterior segments of 

 the Wolffian body by a number of vasa efferentia, the ar- 

 rangement of which is treated of on pp. 257, 258. The section 

 of the Wolffian duct which overlies the Wolffian body is much 

 contorted, and in adult individuals at the generative period enor- 

 mously so. The duct often presents one or two contortions 

 beyond the hind end of the Wolffian body, but in the normal 

 condition takes a straight course from this point to the unpaired 

 urinogenital cloaca, into which it falls independently of its 

 fellow of the opposite side. It receives no feeders from the 

 kidney proper. 



The excretion of the kidney proper is carried off not by a 

 single duct, but by a series of more or less independent ducts, 

 which, in accordance with Prof. Semper's nomenclature, will be 

 spoken of as ureters. These are very minute, and their inves- 

 tigation requires some care. I have reason, from my examina- 

 tions of this and other species of Elasmobranchs, to believe that 

 they are, moreover, subject to considerable variations, and the 

 following description applies to a definite individual. Nine or 

 possibly ten distinct ureters, whose arrangement is diagram- 

 matically represented in fig. 1, PL XIX., were present on each side. 

 It will be noticed that, whereas the five hindermost are 

 distinct till close to their openings into the urinogenital cloaca, 

 the four anterior ones appear to unite at once into a single 

 duct, but are probably only bound up in a common sheath. 

 The ureters fall into the common urinogenital cloaca, imme- 

 diately behind the opening of the Wolffian duct (so far as could 



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