874 PROF. G. C. EOURXE ON THE [ISTov. 17^ 



primitive Aspidobrancliia, with Pleurotomaria, Haliotis, Trochus, 

 Cemoria, we find that the gonaduct enters the kidney at no great 

 distance from its external aperture, and close to the reno-pericardial 

 canal, when this structure is present. The glandular part of the 

 kidney lies behind the entrance of the gonaduct. It would he 

 contrary to what we see in all other forms if we were to find, as. 

 we should if Thiele's view were correct, the glandular part of the 

 kidney situated in front of the opening of the gonad and the 

 reno-pericardial canal, between these and the renal pore. The 

 presence of an anterior lobe of the right kidney in Pleurotomaria 

 and Haliotis does not invalidate this reasoning, as may readily be 

 seen on consideration of its relation to the ureter or non-glandular 

 part of the kidney. But, it may be asked, if the complex of 

 glandular tissue and ducts lying in front of the oviduco-co?lomic 

 funnel in the jSIeritidfe do not represent the glandular part of the 

 kidney, what do they represent ? I have no doubt that they are, 

 in large part, analogous to the modified glandular terminal part 

 of the ureter described by M. F. Woodward (41) in Pleurotomaria, 

 or, to seek a nearer homology, to the glandular sac forming the 

 ureter in the left functional kidney of the Neritidfe themselves. 

 I have already instituted a comparison between this glandular 

 ureter and the various glands found on the course of the ootype 

 and egg-duct, and have given reasons for belieA'ing that both are 

 derived from an invagination of the mantle- epithelium. If these 

 comparisons are correct, the conclusion follows that the ovipository 

 aperture in the female and the single pore of the male are the 

 representatives of the ureter of the right side. The vaginal 

 aperture of the female has therefore nothing to do Avith the 

 primitive right renal opening. As to how it has been established 

 I will not, in the absence of embiyological evidence, hazard an 

 opinion. I will merely point out that the formation of accessory 

 sexual ducts is a common phenomenon. The ductus enigmaticus 

 of Septaria and Paranerita is an example. So also are the vaginal 

 ducts of the triaulic Doridid?e and Elysiidte. In the Platyhelmia 

 multiplication of the female orifices, e. g. in Trigonoporus, is 

 common ; and I do not think it altogether fanciful to say that, 

 there is some analogy between the Laurer-Stieda canal of Tre- 

 matodes and the ductus enigmaticus of the ISTeritida?. 



The spermatophores of Nerita and Paranerita require some 

 description. They are very similar in general appearance in all 

 species I have studied. As shown in fig. 69, a spermatophore 

 consists of a cylindrical body, rounded at one end and produced 

 at the other end into a long liollow filament. In several cases I 

 have seen this filament engaged in the aperture of the vaginal 

 canal, as represented in fig. 64, and extending for a long- 

 distance into its lumen. It is therefore evident that the contenta 

 of the spermatophore — the spermatozoa — are voided through the 

 filament into the lower end of the vaginal canal, possibly into the 

 receptaculum seminis, and do not pass into the lumen either of 

 the vagina or of the upper part of the vaginal canal. Usually 



