MEMORANDA. 147 
Permit me to make a few observations on his interpretations 
of the generative organs of those animals. Having had occa- 
sion to dissect a specimen of Helix aspersa, I was struck with 
the immense number of zoosperms to be found in the gland 
which Dr. Lawson calls the ovary, and on further investiga- 
tions on other specimens, as well as on Arion empiricorum 
and on specimens of the genera Limneus and Planorbis, I 
find I can quite bear out the anatomy as given by Gegen- 
baur, as I have before me preparations of ceca of this gland, 
which show the zoosperms in situ in the centre, with ova in 
all stages of development towards the periphery, but I can- 
not make out any double membrane as described by Meckel 
and Siebold. 
The presence of zoosperms in this gland is, I think, con- 
clusive as to its being a testicle as well as ovary, for they are 
too numerous to have come in accidentally, and their presence 
in ceeca in which all the ova are too young to be impregnated 
show that they are not derived from some exterior source for 
that purpose, which is also very improbable on other grounds ; 
the duct is also stuffed full of zoosperms, and it seems strange 
that Carus should have taken them for ciliz. 
Dr. Lawson thinks that the prostate is the testis; but the 
fact that in the Planorbis the male duct separates from the 
uterus and, receiving the secretion of the prostate in its 
course, goes on to join the sac of the male opening, shows 
that the prostate is simply an accessory organ. 
I shall be happy to show Dr. Lawson the preparations 
above referred to, and apologising for occupying your valuable 
space.—A.rrep Sanpers, M.R.C.S., F.L.S., 22, Beaufort 
Villas, Brixton. 
VOL. IV.——-NEW SER. L 
