192 
HISTORY OF BRITISH CRUSTACEA. 
creatures. Among these, and assisting to conceal and me- 
tamorphose the plant, you may find a number of conical 
tubes, varying from one-sixteenth to one-eighth of an inch 
in length, made of a somewhat tough papery or leathery 
substance, of a dusky colour, and of a rough surface. They 
are stuck upon the fronds of the seaweed in all directions, 
without any order, some laid along, others standing erect ; 
sometimes singly, sometimes associated. From the open 
extremity project two pairs of stout jointed antennae, both of 
which are armed on their under edge with double rows of 
spreading spines, like those of the interior antennae in Ca - 
prella. These well-armed organs are affixed to a large oval 
head, just in front of two black eyes, and are thrown about 
incessantly, forcibly clutching at the water, or rather at 
whatever may be passing in the water. The head ordinarily 
just projects from the mouth of the tube sufficiently to see 
what is going on without, and what prospect there is of 
a successful throw ; but sometimes the creature protrudes 
his first two pairs of feet. . . . The animal in its tube much 
resembles the larva of the genus Tliryganea, that anglers 
value under the name of Caddis-worms. There, however, 
the case is composed of minute pebbles, bits of shell, etc., 
imbedded in a glutinous silk, with which the interior is 
