AND THE LOWER ANIMALS. 101 



the Lerneae, or fish-lice, as they are termed, than in the 

 Cirrhipedia. Among the Lernea3 the degradation of 

 the being extends much further than we should 

 imagine possible. 



The young lernea is a genuine crustacean when it 

 emerges from the egg. At first it is like a cyclops 

 larva ; it has eyes, and swims freely about by the aid 

 of two feet, each of which ends in a large bunch of 

 filaments. During the second period of its existence, 

 it has three pairs of feet in front, and as these are 

 provided with hooked claws, they are equally well 

 adapted to assist in locomotion or to grasp the smooth 

 skin and gills of fishes. At this period, moreover, it 

 acquires four posterior swimming feet, and a tail or 

 abdomen like that of other Crustacea. Up to this, 

 metamorphosis was elevating the being more and 

 more ; it now begins to destroy what it has con- 

 structed. 



In assuming the adult condition, the female grows 

 to an immense size ; two of her anterior appendages 

 become more developed, curved in a semicircular 

 manner, and united by their extremities, which ter- 

 minate in a sort of projection, are plunged into the 

 tissues of the animal upon which she is parasitic, and 

 then fastened there permanently ; two others, reduced 

 to mere hooklets, attach in a similar manner the 

 mouth, which is converted into a sucking organ ; the 

 remaining appendages disappear, and the body, in- 

 flated and deformed, is now but an irregularly- shaped 

 pouch, containing a stomach and a quantity of ova. 

 At the same time the male, disfigured to a lesser 

 extent, but still two or three hundred times smaller 

 than the female, attaches himself to the body of his 



