98 CRUSTACEA. 



terms in natural history with their scientific Umits, the king 

 crab of the tropical seas belongs to a totally different order 

 of Crustacea than either of those above mentioned, whilst 

 the hermit crab belongs to the Macroura. 



Crabs are for the most part marine animals, frequenting the 

 rocky shores of the ocean. We regret the very slight attention 

 which has been paid to the habits of these marine animals. They 

 are found in all latitudes, but are more abundant in the warm and 

 temperate climates than in more northern regions. Some genera, 

 as Ocypoda, Gecarcinus, Uca, Grapsus, &c., frequent more southern 

 regions, being found in nearly equal latitudes, in the different 

 parts of the old and new world. Otliers, as the true crabs, Por- 

 tunus, &c., are more generally distributed, extending from the 

 equator to the polar chcles. 



The local habitations of these animals are, however, very varied. 

 Some species, although having the form of marine crabs, do not 

 quit the fresh water, as in the Teljjhustp. Again, amongst the 

 marine species, tlie majority do not quit the shores, whilst others 

 are found at great distances in the high seas, where they can rest 

 only on the floating banks of sea-weeds, so abundant in the tropics. 

 And even in those species which frequent the coasts, the same 

 situations are not congenial to them all : some, as Dorijjpe and the 

 Inachi, reside at great depths of the sea, from two to four hundred 

 feet, whilst others keep continually at the surface of the waters, 

 passing a great part of their existence upon the shores continually 

 washed by the waves. Some species, again, frequent only the 

 rocky parts of the coast, abounding in madrepores and difficult 

 of access, v.'hilst others prefer sandy shoals, in which they bury 

 themselves. 



Amongst the land crabs some species, as the Ocyjjodce, make deep 

 burrows, at the mouth of which they ordinarily take their station 

 after the fashion of sentinels, whilst some, as the Ranince, prefer 

 more elevated places, and sometimes even mount the roofs of the 

 huts of the Indians. The crabs are, indeed, the most active ani- 

 mals of the class with reference to their powers of walking, although 

 the Macroura certainly excel them in s\Almming. In those crabs 

 Avhich run fastest the eight hind legs are alone employed, and are 

 terminated by strong pointed hooks. They walk with the same 

 facility, forwards, backwards, and from side to side, indeed in aU 

 possible oblique directions. They will also ascend inclined planes, 

 and even almost perpendicular surfaces, pro\ided these planes be 

 not quite smooth. Many, as the OcypodcE and Gecarcini, are noted 

 for tbeir rapidity in running ; indeed it is said that a man at full 



