CRUSTACEA 227 



3. Brachyura 



Libinia emarginata Leach (Spider Crab; Sea 



Spider) 



PLATE XXVI. Fig. 2 



The common Spider Crab of the New Jersey 

 coast; very common on sandy and muddy grounds 

 from shallow water to 25 fathoms, rarely deeper; 

 found in bays and inlets as well as in the open ocean. 

 The carapace of the Spider Crab is often covered 

 with hydroids, sponges or algae which serve to mask 

 the crab and make it invisible to its enemies. The 

 median line of the carapace has about nine spines. 

 Known from Maine to Florida. Of no commercial 

 value. Sometimes reaches a foot or more in size, 

 usually smaller. 



Different from the Blue Crab (CaUinectes sapi- 

 dus) in that the claws of this crab are not at all 

 sharp and one may pick it up without danger. 



The Spider Crab occasionally lives as a com- 

 mensal within a jelly-fish. 



Libinia dubia Milne-Edwards (Spider Crab) 



Six median spines instead of nine and with a 

 longer rostrum (beak); similar habits to the above. 

 Not as common. 



Hyas coarctataus Leach (Toad Crab) 



The affinities of this to the Spider Crabs are 

 obvious, but it strongly resembles a toad. A north- 

 ern species not seen in New Jersey since Leicly 



