MALACOSTRACA. G 43 



the feet are attached ; these, for the most part, have a tail, con- 

 sisting of many segments. The limbs vary from six to four 

 teen, each having six articulations. The two front limbs, and 

 sometimes even three on each side, are provided with pincers 

 at other times they are terminated by simple hooks, and not un- 

 frequently, they have appendages which fit them for swimming. 

 There are two mandibles, a lip below, and from three to five 

 pairs of jaws ; these small, leg-shaped appendages are not 

 adapted to locomotion, but being placed near the mouths, assist 

 in the operation of feeding. 



The eyes vary in number, usually being compound, seated on 

 peduncles, which are sometimes movable, and at others fixed. 

 Some of the parasitic species are destitute of eyes in their per- 

 feet state, though possessing them when young and able to swim 

 about. The Crustacea have the senses of taste and hearing, 

 probably also have that of smelling, though the precise location 

 of its organ has not been ascertained. Some of them have the 

 power of emitting light in the dark. Others are able not only 

 to detach one of their limbs when seized upon by an adversary, 

 but can reproduce the severed limb. This, however, is always 

 of a less size than the others, until it has once or twice changed 

 its crust. 



The Crustaceans include five orders. 



FIRST ORDER. MALACOSTRACA, (Gr. /uahaxbg, malakos, soft ; 

 oaryuxov, ostrakon, shell;) or Decapoda, (Lat. ten-footed.) 



This Order is divided into two sections. (1) Brachyoura, 

 (Gr. short-tailed,) including the CRABS, the species of which are 

 various in size, color, and modes of living, having bodies covered 

 by an external skeleton or calcareous crust, with ten articulated 

 limbs, adapted for swimming and for walking also, (with oblique 

 stops.) and breathing by gills. They have two pincer-like claws, 

 and jointed antennae, and throw off their crust annually, at the 

 end of spring. When they have lost a pincer or foot, it is repro 

 duced with the new shell, and also at other times. When their 

 legs or claws become injured or are touched with a hot iron, 

 they themselves cast them off. The material out of which the 

 new shell is hardened, is furnished by two calcareous con 

 cretions, called Crabs eyes, found in summer on both sides 

 of the stomach. These animals live on dead bodies, pu 

 trid flesh, and all descriptions of worms and insects found in 

 water. Our references to species must be confined chiefly to 

 those noticed on the Chart. The EDIBLE CRAB, of England and 



