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 Miiller 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 lirst) is much larger than in the female, that it has the 

 form of a very large hook, strongly curved outwards, and that 

 the set« 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 antennge, 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. 

 Jurine ; 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, whence it is introduced into the ovaries ; but analogy 

 seems hostile to such a conjecture. Jurine has witnessed 



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