608 
ARTICULATA. 
upon the sandy beach in search of his prey ; but the moment danger threatens him he disappears 
into his cell, the orifice of which is then occupied by one of his claws, which is always larger than 
the other. As the crab does not possess the same power of adding to the size of the domicile 
that was enjoyed by the original tenant, he is compelled, from time to time, to change his 
residence for one a little larger, and often appears almost as difficult to please as a human house- 
holder in the same predicament. Often they may be seen crawling about among the shells 
just thrown upon the beach, trying one 
after another, until they meet with one 
uniting all the conditions requisite for crus- 
tacean comfort ; but, until this great ob- 
ject of their search is attained, always 
returning to their old house after each un- 
successful trial. It is said, indeed, that 
when two of them happen simultaneously to 
cast a longing eye upon some particularly 
suitable residence, they often engage in a 
fierce battle for the possession of the coveted 
object, which the victor carries off in tri- 
umph. 
The Purse-Crab, Birgus latro, is a 
very curious species found in Amboyna 
and some of the adjacent islands. They 
inhabit the fissures of rocks along the sea- 
shore by day and come forth at night to 
search for food along the beach. When 
they meet a person they set up their claws 
in a threatening manner and snap their 
pincers and retreat backward. The natives 
say they climb the cocoanut-trees to get 
the cocoanuts. 
THE PURSE-CRAB. 
THE BRACHYUEA. 
This term is from the Greek brackus, short, and oura, tail, and includes the Short-tailed Crabs, 
of which the Common Crab may be taken 
as the type. 
THE MAIAD^. 
THE SPINOUS SPIDEE-CRAB — STAIA SQUINADO. 
This includes the Spider-Crabs or Sea- 
Spiders : in these the legs are long and 
hairy ; the back is usually covered with 
spines and hairs. They generally live in 
deep water, and rarely approach the shore. 
One species, the Libinia canaliculata, is 
common along our coast from the Chesa- 
peake northward. It is said to frequent 
the oyster-beds, and to devour large quan- 
tities. 
THE CANCEEID^. 
The gemis Cancer of Linnseus included the Crabs generally, many of which, though bearing 
the general form of the more common species, are still possessed of very peculiar and remarkable 
features. The Eriphia spinifrons^ for instance, distributed in nearly all seas, has the front covered 
with numerous sharp spines ; and the Parthenope horrida, a native of the Atlantic and Indian 
