Mr. C. Spence Bate's Notes on Crustacea. 109 



XI. — Notes on Crustacea. By C. Spence Bate. 



[With a Plate.] 



Male Organs in the Brachyura. 



I. The so-called false feet in the male Brachyura differ materially 

 from those of the female, in both of which they serve an efficient 

 purpose, that of assisting towards the development of a future 

 generation. 



In the female they form supports on which suspend the ova, 

 imtil they are matui'ed. so far as to exist as independent creatui'es. 

 But in the male they are more directly concerned in reproduc- 

 tion, being in fact the external sexual organs. 



I am aware that the highest authority, M. Milne-Edwards, 

 both in his ' Histoire des Crustaces,' as also in the ' Cyclopaedia 

 of Anatomy,' article " Crustacea," has denied this office to these 

 organs, but I have frequently had ocular proof of the fact, having 

 several times last summer taken Carcinus mcenas in the act of co- 

 pulation, under which circumstances I distinctly saw these sty- 

 liform processes deeply inserted within the vulvse of the female. 



Since the above observations, I have given much attention in 

 order to make out the whole anatomy of the part, which I have 

 endeavoured to do by examining Carcinus mcenas, Portunus puber, 

 Cancer pagurus and Xantho rivulosa. They consist of two pair, 

 the larger being anterior and attached to the first abdominal 

 ring ; the less or posterior to the second ring. In all except the 

 edible crab, the second pair is very small, apparently rudimen- 

 tary, and lie with their extremities inserted posteriorly into the 

 larger pair. But in Cancer pagurus, though slight, they are 

 equally long with the first pair, and have a joint peculiar to this 

 crab situated near the centre, in addition to one, common to 

 others, attaching it to the basal joint. The orifice of this pair is 

 slightly frilled ; it lies posteriorly against the first pair, which 

 are the more important ; these latter are styliform processes at- 

 tached by a hinge to a calcareous continuation of the inferior 

 dermal membrane of the abdomen, from the anterior centre of 

 which extends a process which I presume assists both in the 

 erection of the organ and the extension of the abdomen from the 

 usual position beneath the thorax. 



From the first joint of the fifth pair of legs (some having an 

 orifice through the calcareous shell distinctly for its own passage, 

 as Cancer pagurus, others opening through the fiexible mem- 

 brane, while in others again a notch exists which more or less ap- 

 proximates a separate opening), a meinbranous tube, being the 

 vas deferens, passes out and enters at the second joint of the 



