344 
CLASS CRUSTACEA 
The males, at least in the species observed by M. Straus, 
are very distinct from the females. The head is proportionally 
shorter; the back is less projecting. The valves are less 
broad, and less gibbous superiorly, and they gape in front, so 
as to present, in this place, a broad and almost circular aper- 
ture. The antennae are much larger, presenting the appear- 
ance of two horns directed downwards, and have been con- 
sidered by Muller as the sexual organs in the male. These 
sexual organs, M. Straus was unable to discover, but he has 
remarked that the onglet, terminating the last articulation of 
the two anterior feet, (the second, supposing the oars to be 
the first) is much larger than in the female, that it has the 
form of a very large hook, strongly curved outwards, and that 
the setae of the third articulation is also much longer. These 
hooks answer the purpose of seizing the female. The nipples 
of the sixth segment of the abdomen, are much less visible, 
and have the form of tubercles in early age. With the ex- 
ception of the lower antennae, much longer in the males, the 
two sexes nearly resemble, and the two valves of the shell are 
terminated in both, by a stylet, denticulated underneath, 
arched towards the bottom, and of a length almost equal to 
that of the valves. At each moulting, this stylet grows shorter, 
so as to form, in the adults, only a simple obtuse point. 
The males are very ardent in the pursuit of their females, 
and often of the same individual. 
A single act fecundates the females for several successive 
generations, as far as six at least, as has been proved by M. 
J urine; M. Straus remarking that the orifices of the ovaries 
are placed very deeply under the valves, and that, therefore, 
no part of the body of the male could reach them, suspects 
that there is no copulative organ in the latter, and that he 
only ejaculates the fecundating fluid under the valves of the 
female, wdience it is introduced into the ovaries ; but analogy 
seems hostile to such a conjecture. Jurine has witnessed 
