DEC APOD A OR CRABS, LOBSTERS, ETC. 357 



garded as the highest members of the Decapods, and 

 together they constitute a great group called the BRACHY- 

 UEA, from the Greek bravhus, short, and oura, a tail. 

 These crustaceans have the hind body or abdomen popu- 

 larly called the tail shorter than the cephalo-thorax, and, 

 in a state of rest, brought forward under the latter, where 

 it fits into a groove. In the males, the abdomen is 

 triangular, and furnished at the base with two or four 

 horn-like appendages ; in the females, it is wider, and 

 has beneath it four pairs of double hairy appendages to 

 which the eggs adhere when they are laid. 



Crabs vary in size from a fraction of an inch across, to 

 those which, with the legs spread out, cover a space of 

 more than a yard square. 



FIG. 481. 



American Edible Crab, Lupa dlcantka, Milne-Edwards. Reduced one half. 



Crabs undergo great changes after they leave the egg, 

 before they acquire the form of the parent. In a word, 



