DECAPODS : MACRURANS. 463 



neath it four pairs of double hairy appendages to support 

 the eggs. Such are the Crabs, of which there is a large 

 number of genera and species, varying from a very small 

 size to those which, with all their appendages, cover an 

 area of two or three feet square; their forms also are 

 almost endlessly varied. They walk with equal facility 

 forward, backward, sidewise, and oblique. The Anomu- 

 rans are represented by the Hermit Crabs, Pagurus, 

 which inhabit the spiral shells of dead Gasteropods. 



The Macrurans comprise long-tailed decapods, those 

 which have the hind body as long as the cephalo-thorax, 

 and generally curved downwards and forwards, as Lob- 



Fi 3 . 363- 



American Lobster, Homarus americanus, DeKay. 



sters, Cray-Fishes or Fresh-water Lobsters, Shrimps, and 

 Prawns. Homarus contains the American Lobster, H. 

 americanus, DeKay, which is from one to two feet long. 



The Gastrurans Stomapods, Latr. contain those 

 decapods which have the viscera extending into the ab- 

 domen, and the feet mainly approximating the mouth. 

 Their general form bears considerable resemblance to 

 that of Shrimps. They are all marine. Squilla, con- 

 taining the Sea Mantes, is a characteristic genus. 



