I20 The Irish Nahiralist. [May, 



THE CRABS OF OUR SBA-SHORK. 



BY W. H. CUNNINGTON, A.R.C.SC. LOND. 



[Read before the Dublin Naturalists' Field Club, 12 December, 1899). 



Thk crabs of the Irish area have by no mean-s received the 

 attention they deserve, and in consequence, we have not yet 

 such satisfactor}' lists of the forms which have been found, as 

 we should, and easily might have. I laj^ stress upon this 

 particularly, because it affords an opportunity^ for the members 

 of this Field Club. Kverj^one, at some time or another, has 

 foitnd crabs, whole or fragmentary^ during walks along the 

 shore. The fishermen, too, frequently bring in with their 

 more valued relatives, a variety of strange crabs, which might 

 be easily secured, as they are of no use to them. Again, crabs 

 are almost entirely identified b}^ peculiarities of external 

 structure, and so to a large extent, a dried specimen will 

 answer for our purposes. Thus, a specimen not very fresh, or 

 even an empty shell, would not be necessarily valueless. 



The habits of crabs, as of other animals, are largely reflected 

 in their form and structure. That is to say, we may expect 

 to tell at a glance, by some very striking differences, whether 

 we are dealing with swimming crabs or running crabs, with 

 burrowing crabs or land crabs. This in fact is the case, and 

 we may always recognise a swimming crab for example, hy 

 the flattened condition of his legs, while the last joint of the 

 last pair of legs is generally expanded and plate-like. 



Coming to deal with particular forms, I should, perhaps, 

 mention first the Grken Crab {Ca7'chnis vioenas), as it is 

 undoubtedly the most common on our shores. This creature 

 belongs to the group of the swimming crabs, although it can 

 run about on land well enough, and has not attained to the 

 flattened end of the fifth leg, so characteristic of its relations. 

 The shell, too, which is somewhat broader than long, has the 

 front edge divided up into a number of prominent teeth. 

 These crabs do not ever grow ver>^ large, but perhaps make 

 up for this in numbers, as they may always be found on our 

 shores, lurking in little rock-pools and beneath stones and 

 sea-weed. Their food, in common with most crabs, consists 

 of young fish, small shrimps, and suchlike; but they are 

 greedy little things, and no kind of animal refuse seems to 



