CANTHOCAMPTUS. 
207 
has both stalks divided into three articulations, the ex- 
ternal having all three of nearly an equal length, whilst 
the internal has the first articulation nearly as long as all 
the three of the external put together, but the last two 
short, and inclined outwards. The three succeeding pairs 
(f. 5 g, Ji) have the internal stalk shorter than the external, 
both consisting of three joints, though Jurine says the 
external has five. The fourth pair are the longest of all. 
The fifth pair (f. 5 i) are small, and rudimentary. They 
are situated under the fifth segment, and consist each of 
a flat body, from each side of which issues an appendage 
furnished with several hairs, the external being the longer, 
and giving off a number of setae also from its external edge. 
In the male they have been considered as the organs of 
generation. 
At the base of the sixth ring in the female are the 
openings of the canalis deferens, and under the sixth and 
seventh segments the adults of the same sex carry a very 
singular, horny -looking, club-shaped organ, which is 
fastened to the body by a narrow, elongated stalk. It is 
somewhat curved, and directed backwards; its colour 
being almost always more or less of a red hue. This organ 
is not found in the young female, nor till after she has 
several times laid eggs. Its hardness is greater than that 
of the shell or carapace of the animal. Jurine has seen 
two in one female, one red, the other black. Its use is 
unknown. 
M. Siebold has conjectured its use to be the same as 
that of the elongated tubes occasionally seen in the females 
of Diaptomus (see the description of that genus) ; and 
asserts that he has seen these bodies suspended over the 
genital region of the female, and still inclosed in the 
deferent canals of certain males, which by their antennae 
were attached to the tail of the female. He never saw 
the male, however, fasten this body to the female. 
Jurine says that this body is never seen in the female 
till after she has several times laid eggs. In my own ex- 
perience, I have never seen more than one body attached 
