294 MEMORANDA. 
two feet long, and few tables being less than four feet wide 
or across, it is capable of accommodating from two to six or 
more persons at an ordinary dining-table, or placed on a 
circular centre table, as many as can sit around it. It thus 
becomes, for one instrument, equally useful as the whole 
table would be. 
In common deal it may be made for a very few shillings. 
In solid well-seasoned inch-thick mahogany, French-polished, 
with bronzed iron centre support, corked for steadiness and 
to prevent scatching, and with highly brass runners, it ought 
to be obtained in London for about a guinea or less. The 
builder (himself a very clever hand) whose workmen made it 
for me, is so impressed with the belief in its usefulness and 
the certainty of its being approved when seen, that he has 
volunteered to provide a number of them during the slack 
time of winter, at the lowest possible cost, to be sent out as 
patterns, or he will supply the trade with them, if required.— 
W. Kencrty Bripeman, 69, St. Giles’, Norwich. 
Zoosperms in the ovaria of Pulmogasteropoda.—In reference 
to the above subject I see that Dr. Lawson has proposed, in 
the number of your Journal for July, some objections to the 
common opinion that the ovary in these animals is in reality 
a hermaphrodite gland; they appear to me by no means in- 
surmountable, and with your permission I will do my best to 
answer them. His first objection is, that the zoosperms are 
found fully developed in the ovary, and imperfectly formed in 
the spermatheca, and must therefore have undergone a species 
of retrograde development. This is by no means my experi- 
ence; on the contrary, in the ovary of H. aspersa, I have 
found zoosperms in the immature condition, which he calls 
spermatophora; that is, still united by their heads into 
bundles, and having yet a good deal of the granular contents 
of the parent cell remaining attached; and in the ovary of 
Arion they have occurred in a still earlier stage, so that there 
is no necessity for the hypothesis of retrograde development. 
With regard to his other objections, viz., there being only 
one excretory canal to the ovary, and the impossibility of the 
passage of the zoosperms into the spermatheca, I may state 
that I think I have seen in Helix a small tube situated in the 
connective-tissue, and which surrounds the ovarian duct, but of 
this I am not certain; at any rate, granting that the canal is 
single as far as the abdomen gland, it is just possible that the 
ova are not sufficiently mature to be impregnated, until they 
have passed that gland, and then the structure of the uterus 
