THE CRUSTACEANS 97 
which they feed. They are agile animals, leaping with remark- 
able rapidity. In swimming they often progress on their sides 
or upon their backs with feet upward. 
They are creatures chiefly of the shore 
or of shallow water, although some closely 
related species are found in the deep sea. 
These minute animals are important scav- 
engers, rapidly devouring all dead fishes 
and other forms of decaying animal or 
vegetable matter. They are themselves 
devoured in immense numbers, often by 
the identical species of fishes upon whose 
dead bodies they themselves delight — to 

feast. 
aa eee Tate Tee ee 
Irchestia agilis, Fig. OO, is the common Fig. 66; SAND FLEAS. 
olive green or brown Beach Flea of our coast. 4 g0ve::( Talorchestia lon- 
It grows to be not more than half an inch gicornis). 
long, and lives during the daytime under SE 
masses of sea weeds which have been re 
thrown up upon the beach. It constructs burrows in the sand under 
the debris, and when disturbed it leaps with remarkable strength 
and agility. 
A still larger species is, (T'alorchestia longicornis Fig. 66), 
which is white or gray in color, and about an inch long. It is also 
a beach scavenger, and devours decayed sea weeds, feeding mainly 
at night, and remaining hidden within its burrow during the day. It 
appears never voluntarily to enter the water but is a good swimmer. 
The Wood Borer, or Gribble, (Limnorea lignorum), is related 
to the sow-bugs and pill-bugs and belongs to the sub-order of Crus- 
tacea known as Isopoda. ‘The gribble extends from New York to 
Nova Scotia, and is also abundant on the northern coasts of Europe. 
It is not more than one-fifth of an inch long, and has a flattened 
body with fourteen segments, and seven pairs of short legs. The 
back is covered with short hairs to which foreign substances are apt 
to adhere. It is dull gray in color and resembles a pill-bug, the simi- 
larity being still further enhanced by its habit of rolling up into a 
ball when disturbed. It can also leap and swim rapidly. This crea- 
ture is most destructive to all submerged timber, devouring every 
