606 
ARTICULATA. 
within a cavity on each side of the cephalothorax. The true thoracic legs are almost always ten 
in number — whence the name of the 
order. It includes an immense number 
of species, generally of considerable size 
when compared with the other Crustacea. 
We shall notice them under three sub- 
orders, the Macrura, Ano^nura, and Bra- 
chyura. 
THE MACETJRA. 
This term, from the Greek maTcros, long, 
and oura, a tail, embraces those species 
which are generally called the Long- 
tailed Decapod Crustacea. 
THE CRANGONID^. 
This family includes the well-known 
Shrimps and Praions. They are distin- 
guished by the possession of a large oval 
or triangular appendage which covers the 
base of the first joint of the outer an- 
tennse. In their general appearance they 
all present a considerable resemblance to 
the Common European Shrimp, Crangon 
vulgaris. They inhabit salt water, and 
generally occur in large numbers, found 
together on sandy coasts ; and in spite 
of their small size, they are everywhere 
in great request as articles of food. The 
common shrimp of Europe is about two 
inches long; the Common European 
Prawn, Palemon serratus, is three to 
four inches long. The American Bait- 
Shrimp, Crangon septemspinostcs, and the 
American Prawn, Palemon vulgaris, are 
common on our coasts. 
THE ASTACID^. 
To this family belongs the Common 
Lobster, distinguished from the preceding 
by the small size of the appendage at the base of the outer antennae, besides many other differ- 
ences in fonn and structure. The anterior pair of feet is always much larger than the others, and 
armed with powerful nippers. Some of these animals live in fresh water. These are of a smaller 
size than the marine species, but are also eaten in great numbers by the inhabitants of the neighbor- 
hoods where they occur. Lobsters change their shell annually ; before casting the old shell they are 
sickly and grow thin, and thus, though with great effort and apparent suffering, the old covering 
is cast off, and the new one is speedily formed by secretion. Sometimes lobsters throw off their 
claws in consequence of fright, and often they will hold on to an object till the claws are torn 
off. To some extent these lost parts are reproduced. They are very active in the water, and 
can spring to a considerable distance ; they feed chiefly at night. They are voracious, and eat 
any animal matter that comes in their way. Immense numbers of the European Lobster, As- 
tacus marimis, are taken, but the means of increase are abundant, twelve thousand four hundred 
and forty-four eggs having been found under the tail of a single female. The Common American 
THE SIIEIMP. 
