198 LIFE BY THE SEASHORE. 



Besides Hyas araneus we have another British species 

 H. coardatus which is also very abundant, but occurs in 

 deeper water. It is very much smaller, and is easily 

 recognised by the shape of the carapace. This is suddenly 

 contracted behind the post-orbital processes, so that the 

 regularly triangular shape of H. araneus is lost. Young 

 specimens of this species are sometimes to be found far out 

 on the rocks, or among the weed flung ashore after gales, 

 but are difficult to distinguish from the young of H. araneus. 

 Indeed, some authorities deny that the two species are 

 distinct. 



Belated to Hyas is the genus Pisa, including small, hairy 



FIG. 56. Stenorhynchus phalangium, the long-legged spider-crab. 



crabs, not very dissimilar to Hyas in appearance. The two 

 species are too rare in Britain to merit description. 



The last two genera of spider-crabs are even more spidery 

 than the preceding, and differ from them in the great length 

 of the walking legs, as contrasted with the short and thick 

 great claws. The great claws are especially thickened in the 

 male. 



Under stones at low water there may be occasionally 

 found Stenorhynchus phalangium (see Fig 56), a representa- 

 tive of the first genus. The carapace forms an elongated 

 triangle, and is prolonged into a long tapering bifid rostrum. 

 The protruding eyes cannot be retracted into the circular 

 orbits, and are peculiar in bearing on their surface a tuft of 



