56 



CANCERID^. 



bourhoocl of Nice ;" and Edwards says that it inhabits the 

 western coast of France. In all probability it is identical 

 with X.florida^ " var. j3 digitis concoloribus" of Leach; but 

 Mr. Couch of Polperro was the first to detect it as an 

 English species, and to refer it to its proper name ; and it 

 was also detected by Captain Portlock as an Irish species, 

 a specimen having been obtained at Portruch, in the coun- 

 ty of Antrim. I have been favoured by Mr. Couch with 

 specimens from Cornwall ; I have also received it from 

 North Wales, through the kindness of my friend Mr. Ey- 

 ton. Mr. Couch, writing from Polperro says, '"'' Xantlio 

 rivulosa is common with us, rather more so than X.florida. 

 It is found concealed under stones at low-water mark ; is 

 of rather slow habits, and exuviates much in the same 

 manner as the common crab." There is indeed but little 

 difference in this respect amongst all the true brachyurous 

 forms. 



