CALIGIDiE. 
311 
little animal, and as it can leave the fish upon which it feeds, 
and swim freely in the water, there are many opportunities 
for watching its gambols through its native element. It 
generally swims in a straight line, but it frequently suddenly 
changes its direction, and often turns over and over several 
times in succession.”^ Its swimming-feet are in constant 
motion, and serve also for respiration. Dr. Baird says that 
when it wishes again to fasten itself to its prey, the Argulus 
approaches a fish, and quietly allows itself to be hurried along 
in the current caused by its motion through the water, till 
it touches it, when it quickly attaches itself to the under 
part of the pectoral fins. The males are considerably 
smaller than the females : the latter have as many as four 
hundred eggs, which, having slipped off the fish, she attaches 
in a mass to a stone or some solid body. The female has a 
black mark on each lobe of the abdomen. 
Bam. CALIGIDM, Baird. 
Head shaped like a large buckler, having in front large 
frontal plates. Tour pairs of feet furnished with long plu- 
mose hairs. Antennse small, flat, two-jointed. Second pair 
# British Entomostraca, p. 252. 
