116 CRUSTACEA. 



the EdriopJithalma resort to the shallow margins of 

 the sea, weed-fringed rocks, and tide-pools ; as do 

 the Prawns (Palcemon}. The Sand-hoppers (Ta- 

 litrus) are found by myriads in the rotting heaps 

 of sea-weed that lie on the beach, steaming in the 

 sun ; and the great Lygia oceanica crawls nimbly 

 on the perpendicular sides of rocks that are for 

 many hours left dry by the receding tide. The 

 Hyperice habitually dwell beneath the shelter of 

 the broad umbrella of certain Medusa, whence they 

 roam out on excursions, returning home at pleasure, 

 as I have elsewhere described.* The Corophmm 

 lives in mud at the mouths of rivers, over which 

 it roams when the tide is out, beating the mud 

 with its large and powerful antennae, in its search 

 for prey. 



Among the Podophthalma, or Stalk-eyed CRUS- 

 TACEA, the Shrimps or Sand-raisers (Crangon), 

 and the Thalassinad(Z burrow in sand, mostly 

 in shallow water ; but Calocaris is an exception, 

 for this genus inhabits the mud of the sea-bottom 

 at great depths. Most of the Lobsters and Crabs 

 are inhabitants of deep water, delighting in narrow 

 and inaccessible clefts of rocks, whence they are to 

 be enticed by baited traps sunk in their haunts. 

 Most of these, however, in their earlier life fre- 



rat the weedy shallows ; and several, as Gala- 

 , Porcellana, Carcinus, Pilumnus, &c., are 

 properly shore genera. Portunus and its allies 

 swim with more or less dexterity, by means of 

 their dilated oar-like feet ; while Pagurus takes 

 possession of the deserted shell of some univalve 

 Mollusk, which he drags about with him on the 



* " Devonshire Coast," p. 367. 



