CALIGIME. 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. 



Fam. CALIGIDJE, Baird. 



Head shaped like a large buckler, having in front large 

 frontal plates. Pour pairs of feet furnished with long plu- 

 mose hairs. Antennae small, flat, two-jointed. Second pair 



* British Entomostraca, p. 252. 



