192 J. E. S. MOORE. 



which, like Murox and Paludina, possess two forms of 

 spermatozoa. 



The small normal variety appear to arise one division 

 after the heterotype which terminates the synaptic phase, 

 and the cells out of which these normal spermatozoa are 

 directly formed are, as in most cases, extremely small when the 

 actual characters of the spermatozoa are taken on. On the 

 other hand, the cells which directly metamorphose into the 

 large spermatozoa, or megasperms, are very large, being 

 similar in size and character to the synaptic (growing-cells) 

 themselves. As in a former paper^ I have advanced the view 

 that after the synapsis any cellular generations which may 

 exist are to be considered as potentially ova or spermatozoa, 

 as the case may be, this fact that during the course of the 

 spermatogenesis in Typhobia the small spermatozoa appear to 

 arise two divisions after the formation of the synapsis, while 

 the megasperms appear to be produced directly from the 

 synaptic cells themselves, is extremely interesting. 



Bathanalia. 



The new generic type among the Gastropoda for which I 

 propose the name of Bathanalia is at present represented by 

 one specific form, Bathanalia Howes i, PI. 12, figs. 29, 30, 

 31, 33. As the name implies, this species is found in associa- 

 tion with T. Horei in the deep water of Lake Tanganyika, 

 while in its anatomical features it is so similar to Typhobia 

 that no special anatomical description is required. 



There is only one point in Bathanalia that needs mention. 

 I found after great difficulty, and by the help of sections, that 

 in this genus there is a very slight but quite distinct pallial 

 anastomosis on the right side. 



It is entirely on account of the remarkable characters of the 

 shell that I have thought it necessary to separate Bathanalia 

 as a distinct genus from Typhobia. 



The shell, as will be seen from fig. 29, is conical, composed of 

 eight angular whorls, which from apex to base carry numerous 

 ' * Quart. Jouru. Micr. Sci./ vol. xxxviii, p. 292. 



