96 The Irish Naturalist. May, 



tion, slightly further modified, and of a different shape, is 

 found in V. pcllucida (figure K; specimen from Penshurst) ; 

 and it seems probable that the male organ and its flagellum 

 is what has been described as a globular spermatheca ; there 

 can be no doubt at all about the real spermatheca, which 

 opens into the vagina, and not into the atrium. I have re- 

 ferred throughout to this highl}^ glandular organ {ft. in the 

 figures) as the flagellum, because I think that histologically 

 it is without doubt the same as the organ usually so called ; 

 there is perhaps nothing to show whether the filiform or the 

 obovate type is the older, but certainl}^ the latter seems more 

 perfect in function. The central canal varies considerably in 

 width, according to the condition of the individual ; sometimes 

 it is straight, sometimes spirally convoluted. 



In figure F these organs are seen as the}^ appear when dis- 

 sected out entire from a fixed specimen ; figure G shows the 

 same from the inner side. The letters vi.e. and f.e> mark the 

 male and female parts of the epidid3^mis. Figure G also 

 shows the form of the ovotestis, which lies in the living 

 animal just below the point of the " balancier." The sper- 

 matozoa have acrosome, nuclear portion, mesosome, and axial 

 filament each of about the same length, and there is a long 

 flagellum. Exclusive of the flagellum, their length is 15 to 

 18 /i. 



In V. pcllucida the flagellum and intromittent apparatus do 

 not always appear so largel}' developed as shown in figure K. 

 At such times tlie}^ are very easil}' detached from the wall of 

 the atrium ; and I was unaware of their existence until I found 

 a specimen in which the}' had reached the acme of develop- 

 ment ; after which, on searching in other specimens more 

 carefully, I have always found them occupying precisely the 

 same position as the corresponding organs of V. pyrenaicay 

 which vary in size much more than the rest of the apparatus 

 does, but are never difficult to find, judging from the ten 

 specimens that I have seen ; although even in V. pyrenaica 

 the}' are very easily detached from the atrium. They should 

 be compared with the corresponding parts of that very in- 

 teresting species, Agriolimax agrcstis, in the anatom\' of which 

 there are several points of unique interest. In Vitrina the 

 flagellum may be always demonstrated in sections, even when 



