194 SWIMMING CRABS. 



that run out from the foot of Byng Cliff, I found 

 in Septemher a full grown specimen of the Velvet 

 Fiddling Crab {Portunus puber). All the Crabs of 

 this family, which contains a great number of species 

 and not a few genera, are distinguished at once by a 

 peculiar modification of the hindmost pair of feet, for 

 the performance of an important function. They are 

 all Swimming Crabs, and the facility with which they 

 can roam through the element they inhabit, depends 

 largely on the completeness of the modification which 

 I refer to. Our common Eatable Crab, the bulky, 

 thick-clawed, livid 8-pounder, that lies with all his 

 ten pairs of feet so meekly folded across his breast, 

 can swim — about as well as a stone of the same size. 

 Now examine his hindmost feet ; their single toe ta- 

 pers to a sharp point in no wise differing from those of 

 the four pairs that precede them. But the Portunidoe, 

 or Swimming Crabs, have this last pair of feet much 

 flattened out side- wise, and the toe in particular dilated 

 into an oval thin-edged plate, which striking obliquely 

 upon the water acts as an oar, with that peculiar 

 action which is known to boatmen as sculling. In 

 the common Shore-crab {Carcinus maenas) ,th&i abun- 

 dant olive-green kind which on every rocky shore 

 little boys and girls catch, by letting down into the 

 crevices a piece of string with a fragment of offal tied 

 to it, — we observe a transition condition of the hind- 

 foot ; there is a decided tendency to an ovate form, 

 though the tip is yet taper and acute. And the habits 

 of the animal agree with this structure. The power 

 of shooting slantwise throusrh the water exists, which 

 bears the same sort of relation to the free and easy 



