TROCHUS. 319 
This is a very unusual position, but it may be the right one, 
as I think I have seen at its base the point of issue of the vas 
deferens. Under these peculiar circumstances, how is the 
necessary contact effected? It will appear below, that there 
is reason to think all the Zrochi are invested with that modi- 
fication of hermaphroditism which requires mutual congression, 
as in Helix. 
To support these views, or rather conjectures, of herm- 
aphroditism, I have to observe, that besides the organ pre- 
sumed to be the male générateur, which is never absent in the 
larger Trochi that admit of examination, I have, m numerous 
examples of 7. tenuis, T. ziziphinus, and im at least a hundred 
and fifty 7. lineatus, as well as in 7. cinerarius and T. umbi- 
licatus, invariably found the cloven orifice of the matrix placed 
below the rectum, the canal of which passes partly under and 
around the sac of viscosity to the ovarium in contact with 
the liver; and on the side of that viscus, more posteriorly, 
there is an elongated, subconical, yellowish-white mass of 
much firmer consistence, which I take to be the testis. If 
there be no error in what we have stated, we must consider the 
Trochi as hermaphrodites, and a transition-group from the 
Patellide and Helicide to the strict bisexuals. In addition I 
may state, that on forty or fifty 7. ineatus bemg immersed in 
warm water, all discharged a mass of ova, forced from the 
matrix prematurely. To test this fact, I put as many Litto- 
rina littorea under similar discipline, and only the females 
ejected ova. It is necessary to mention that in the minor 
Trochi, viz. m T. Cutlerianus, T. serpuloides and T. nitens, there 
is a rather long, flat, smooth filament, which, until the present 
discovery, I considered a male appendage, horizontally exserted 
close under the right tentaculum, but which, if the Trochi 
are hermaphrodites, must be regarded as a kind of feeler, and 
perhaps of similar nature to that I have observed in the same 
situation in some of the Rissoe; but the larger species do 
not show such an exserted organ either in a living or dead 
condition. J am aware that im some mollusca, particularly 
the Littorina littorea, the organe générateur is much atte- 
nuated, though not to the extent of obliterating all appearance ; 
