CIROLANA. 249 



five rings of abdomen in general well developed and almost 

 always distinct from each other ; the last false legs termi- 

 nating in two plates. Head generally small. First three 

 pairs of legs generally (or sometimes all) with a strong claw, 

 enabling most of the species to attach themselves to fish and 

 to hold on. 



Most of the species are more or less parasitic, being at- 

 tached to fish, to which they can adhere by means of their 

 strongly-hooked legs. In some parts of the United States* 

 the fishermen say that the fish-lice are " necessary to the 

 life of the fish, and as a proof of it, they observe that if the 

 louse be taken from him, the fish will die, although thrown 

 into the water ; but it is probable that the death of the fish 

 is not owing to the removal of the parasite, but to its being 

 withheld too long from the water." 



Gen. 128. CIROLANA, Leach. 



Abdomen six-jointed. Eyes granulated. Small plates of 

 the posterior ventral appendages larger and wider than the 

 inner. The legs have very small claws, and are adapted for 

 walking. 



Cirolana Cranchii, Leach. (Plate XIY. fig. 3.) — 



* Say, Journal Acad. Nat. Sc. Phil. i. p. 396. 



