274 ARTICULATA. CRUSTACEA. 



lies, of which the Crab and the Lobster may be re- 

 spectively taken as the representatives. 



FAM. I. BRACHYURA,* CRABS. 



Every one is familiar with the general form of 

 these animals, whose distinctive mark is, that the 

 abdomen, commonly called the tail, is shorter than the 

 thorax, or the chest, and folded under it, where there 

 is a sort of groove to receive it. The abdomen, or 

 tail, is of a triangular form and flat in the male; 

 but in the female it is wider, and becomes convex, 

 the eggs being carried about in large clustered 

 masses between it and the thorax, preserved from 

 falling out by four pairs of hairy filaments attached 

 to the abdomen. The antennae are comparatively 

 short ; the eyes have longish footstalks ; the foot- 

 jaws are short and broad, the outer pair forming a 

 sort of lips. The gills occupy a large space on each 

 side of the chest, composed of broad leaves or plates 

 laid one above another, and pointing inwards, to 

 which the absurd name of " dead mans fingers " has 

 been familiarly given. The general form of the body 

 is somewhat oval, the abdomen being concealed, and 

 the breadth of the thorax being usually greater 

 than its length. 



, short, and oi^a, oura, a tail. 



