258 DIVISION UI. ARTICULATED ANIMALS.— CLASS II. CRUSTACEA. 
Sometimes they frequent cemeteries. Once a year, as the period for 
depositing their eggs draws near, they assemble in numerous companies, 
and, following the most direct line, seek the coast without permitting any 
obstacle to intercept them in their way. After laying their eges in the 
water, they return, greatly enfeebled. It is said that they close the mouth 
of their burrows at the period of moulting; after which operation, and 
whilst still soft, they are reckoned a great delicacy. 
Another interesting group constitutes the genus Pinnotheres (Latr.): 
These are of very small size, of which there are several species, named 
pea-crabs, and which reside, during a portion of the year at least, inside 
various bivalve shells, such as mussels, &e. The carapax of the females is 
suborbicular, very thin and soft, whilst that of the males is firmer and 
nearly globular, and rather pointed in front ; the legs are of moderate length, 
and the claws of the ordinary form; the tail of the female is very ample, 
and coyers the whole of the under side of the body. The ancients believed 
that the pea-crabs lived upon the best terms with the inhabitants of the 
shells in which they were found, and that they not only warned them of 
danger, but went abroad to cater for them. 
Second Fatty oF Decaropa, Macrura. — In the genera composing 
this family, the tail and antennx are much longer than in the former, and 
the shell is narrower and more elongate. With few exceptions the Macrura 
are all marine animals, and never quit the water. 
Bincus. —This genus appears to be a connecting link between the short 
and long tailed crabs. On account of their large size, the solidity of their 
integuments, and the form of the tail, these crabs are not able to lodge in 
shells, but must retire to crevices in the rocks, or hide themselves in burrows 
in the earth. 
LB. Catro. — This species is of a large size, and inhabits the Isle of France, 
where it is called the Purse Crab. It is said to climb the palm-trees for the 
sake of detaching the heavy nuts; but Mr. Darwin, who attentively observed 
the animal on the Keeling Islands, tells us that it merely lives upon those that 
spontaneously fall from the tree. To extract its nourishment from the hard 
case, it shows an ingenuity which is one of the most wonderful instanees of 
animal instinct. It must first of all be remarked, that its front pair of legs is 
terminated by very strong and heavy pincers, the last pair by others narrow 
and weak. After having selected a nut fit for its dinner, the c rab begins its 
operations by tearing the husk, fibre by fibre, from that end. under which 
the three eye-holes are situated ; it then hammers upon one of them with its 
heavy claws until an opening is made. Hereupon it turns round, and, by 
the aid of its posterior pincers, extracts the white, albuminous substance. 
It inhabits deep burrows, where it accumulates surprising quantities of 
