THE LIVING WORLD. 
47 
WORM CRAB. 
(.Lerncea branchialis.) 
SHELL CRAB. 
(Notodromus monachus.) 
liind legs, straightens up its long, lean body, and continuously waves its terrible 
front legs, which allow no prey to escape. The antennae, also, are spined, and 
probably are used in catching prey. 
The Fresh-Water Shrimp, or Brook Flea-Shrimp (Gammaruspulex ), takes 
its name from its active movements when upon land. It frequents the smal¬ 
lest brooks, the tiniest rivulets, or the most rapid and deepest streams. When 
frightened it conceals itself in the mud. It carries the young attached to its abdo¬ 
men until they are large enough and strong enough to shift for themselves. 
The Crayfish, or Crawfish (Astacus fluviatilis ), is next, in the general order, 
to shrimps, which it resembles in many respects, but differs in the following: 
The body is longer and covered with 
a strong shell, in which are located all 
the vital organs. The extremities are 
flexible, but protected by a soft shell 
lying in flat rings, the edges of which 
overlap; the tail is flat, and composed 
of fine scales slightly overlapped so as 
to form a spread. In the extremity 
and tail reside its propelling power, 
the latter being capable of almost incon¬ 
ceivable rapidity of motion, equalling that of a fly’s wing. It has eight legs 
springing out from the belly, where the sheath to the body is slightly separated 
to permit the free movement of the organs that lie along the line of separation. 
In front of the anterior legs and directly under the thorax are the arms, which 
exceed the legs in length and terminate in bony claws 
of great muscular power. These are its weapons of 
defence and the organs used to catch and destroy its 
prey. The eyes are set well forward and on top, and 
at the point are needle-like thorns, on either of which 
are the two antennae, or organs of touch. 
The crawfish , in nearly all respects except size, and 
that it is a fresh-water habitant, is identical with the 
lobster. So nearly alike are the two that the crawfish is 
very frequently called the fresh-water lobster. Its fav¬ 
orite haunts are among flat rocks in the shallow places 
of clear streams, where it- generally lies in concealment 
watching for any water insect that may chance to come 
near. But it will also feed on refuse, especially if of 
an animal nature,’and being extremely pugnacious, will 
kill and devour its kind. The claws and legs are 
i very friable, and in the fierce combats it so frequently wages these are often 
I broken off; but the loss of any of these certainly gives it little, if any pain, 
i and the repair is rapid, new claws growing out again in a few weeks. 
Like the shrimp, its first cousin, the crawfish is largely used for both food 
l and bait, and is accordingly caught by various means to supply these demands, 
i but the more common mode is by enticing it into baited pots, into which it can 
easily enter but may not escape. 
The Lobster, which is classed under the genus Homarus , is the most 
1 important member of this order, not only because he is largest of the genera, 
iflf 
CRAWFISH. 
