VARIOUS SPECIES OF CRABS. 269 



common shore-crab (Carcinns mcenas) we have already 

 seen is, like the shrimp, regarded as " live stock" by 

 aquarium managers, and generally kept in special 

 tanks until required, or provisionally used as a 

 scavenger, to clear away any decomposing animal 

 matter. The edible crab (Cancer pagurus} is too 

 valuable to be thus utilised, especially when the 

 common, and to us uneatable " shore crab " will do 

 as well. The spiny spider crab (Maia squinadd) 

 grows to a large size, and is as attractive among the 

 short-bodied Crustacea as the spiny lobster is among 

 the long-bodied. All the spider crabs are nocturnal 

 in their habits, and are generally so sluggish that we 

 may see miniature forests of zoophytes and sea-weeds 

 growing on their carapaces, or shells as they are 

 popularly termed. It has been proved by Mr. Lloyd 

 and others that one species, at least, is in the habit 

 of daintily decking itself with sea-weeds, &c., as had 

 been stated, and afterwards controverted. Miss G. 

 Stephens has also recorded the fact as occurring in 

 the genus Pisa. The body of the last species is co- 

 vered with tough prickles. Nearly allied to it is the 

 true spider crab (Hyas araneus], one of the largest of 

 British species, if length of limb is to be taken into 

 consideration in measurement ; these long legs having 

 obtained for it the adjectival denomination of "spider 

 crab." One allied British species is the four-horned 

 spider crab (Pisa tetraodon), whose stout carapace is 

 covered, especially along the margin, with strong in- 



