CRABS. ANOMOUROUS DECAPODS; HERMIT-CRABS. 251 



sometimes held up in a beckoning attitude, whence these Crabs 

 have acquired the name of Calling- Crabs. Nearly allied to 

 these, which are all inhabitants of tropical regions, are some 

 small native species, termed Pea- Crabs, which reside, at least 

 during a part of the year, inside various bivalve shells, such as 

 Mussels, &c. The ancients believed that the Pea-Crab lives 

 on the best terms with the inhabitant of the shell in which it is 

 found ; and that it not only warns it of danger, but goes 

 abroad to cater for it ; this, however, is an absurd fiction. 



787. The Decapods of the section ANOMOURA are intermediate 

 between the Short- tailed Crabs, and the Long-tailed Lobsters and 

 Cray-fish ; not having the abdomen reduced to the almost rudi- 

 mentary state, which it presents in the former ; 

 neither having it converted into a powerful 

 organ for swimming, as in the latter (Fig. 477)- 

 There is nearly always a pair of appendages 

 attached to its last segment ; and these have, 

 in some instances, important uses. This section 

 includes the Hippa (Fig. 460) and its allies, 

 constituting the family HIPPID^E; and also the 

 family PAGDRID^, or Hermit-Crabs^ which 

 are very peculiar as to both their conformation 

 and their habits. The tail, or post-abdomen, 

 is of large size, but its envelope is little else 

 than a membranous bag, entirely unpossessed 

 of the usual hardness of the Crustaceous inte- 

 gument, and presenting no division into segments. The thorax 

 itself is not very firm ; and it is only on the claws, which are of 

 large size, that we find the true calcareous envelope. For the 

 protection of their soft tails, the Paguridce resort to various arti- 

 ficial methods. Many of them seek univalve shells, in which 

 they take up their abodes ; attaching themselves to their interior 

 by a sucker, with which the tail is furnished at its extremity, 

 and also holding by the three pairs of appendages, or false legs, 

 which it bears at its hinder portion. When they are feeding or 

 walking, the head and thorax project beyond the mouth of the 

 shell ; but when they are alarmed they draw themselves in, 



