CRAB, the name applied to any of the hrachyurous or short-tailed decapod crustacea, comprising numerous forms, which, with the exception of a very few fresh-water species, are inhabitants of the ocean. In the crabs the abdomen is folded under the chest (cephalo thorax), while the antenna are short and small. The group includes among others the spider crabs (Hyas, Libinia, etc.), which have a some what spherical body with long sprawling legs. The shqre-crabs are represented by the species Cancer, which are among the largest of the order. They have a broad shell or carapace, without a prominent beak, or rostrum. There are nine gills on each side. Of the two species on the New England and Canadian coast, C. irroratus is the more common, and often used for food, and C. borealis is less abundant. A fossil species (C. proavitus) has been detected Packard in a collection from the Miocene Tertiary green-sand beds of Gay Head, Martha's Vineyard. It appears to have been the source from which the two existing species arose by divergent evolution. Allied to Cancer is the mud-crab (Panoprens).
The soft-shelled crab of the markets is Calli nectes sapitlus; it is so called from being cap tured soon after molting, when its shell is still soft. The fiddler-crabs (Geksimus), so abun dant on our shores, dig holes near high-tide mark, closing the entrance with their larger claw. The oyster-crab is soft-shelled from living within the shell of bivalves. (See Com MENSAL'S ) . The land-crabs of the tropics live away from the sea, only going to it to lay their eggs in the water during the spawning season. Most crabs are flesh eaters. They are
very active and are remarkable for their gait, running sideways rather than straight ahead. The rear pair of limbs are generally expanded at the extremities into a blade for swimming. Their development is accomplished by metamor phosis through several successive stages or molts. (See CRUSTACEA). They vary in size from the giant crab of Japan, which is about 18 inches long and 12 inches across the disc, but often has legs over 3 feet in length, to the little pea crabs often found in oysters. The crab forms an article of food for many kinds of fish and is used as human food in various parts of the world. Crabs are generally caught in wicker traps, baited with meat; they are also taken with shallow hooped nets which are baited and hauled rapidly at intervals. The crabs are kept for market in floating pens, and are shipped alive packed in seaweed. (See also HERMIT-CRAB; PALM oa ROBBER CRAB; and the various groups and species above mentioned). Consult Calman, oCrustacea" (in Lankester's (Treatise on Zoology,) London 1909) ; Calman,