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INTRODUCTION. 
its duct is as long as the oviduct. The vagina is 
moderately broad. The. cloaca is short. The exte- 
rior generative orifice is on the right side of the head, 
considerably posterior to the inferior tentaculae. 
Chapter vii. — general remarks upon the junction 
OF different portions of the generative appara- 
tus, AND THE STRUCTURE OF ITS TISSUES. 
The testicle was mistaken by Swammcrdam, Cuvier, 
and others for the ovary, and the latter organ and pros- 
tate gland for two portions of the testicle. A micro- 
scopic examination of these different organs at once, 
very easily settles their true nature : although, even 
without this mode of analysis, we would suppose the epi- 
didymis would indicate the character of the gland of 
which it is the duet, and leave the remaining two organs 
to be considered as belonging to the female apparatus. 
In Helix, the structure of the testicle consists of dense 
fasciculi of short coecal pouches, which are simple, bifur- 
cate, or trifurcate. These contain polygonal spermato- 
phori, which are finely granular with a round nucleus, or 
filled with granular globules of uniform size, or with coils 
or bunches or fasciculi of spermatozoa. The epididymis 
always contains, more or less, and is frequently dis- 
tended with, a white, silky, filamentous substance, com- 
posed of spermatozoa. The latter consist of very delicate 
and, comparatively, enormously long filaments, terminat- 
ing, at one extremity, in a thickened head. They vary 
