IONE. 251 



1SOP ODA . 



NORM ALIA. 



Genus IONE. (Latreille.) 



THIS genus is at once distinguished from all the other 

 Bopyrida, except Argeia of Dana, by the possession of 

 elongated branchial (?) appendages attached to the base 

 of the six anterior pairs of legs in the female, and by the 

 structure of the branchiae affixed at the sides of the tail 

 in both sexes ; all of these in the male, and the posterior 

 pair in the female, are elongated and filiform, whilst the 

 pairs attached to the five anterior segments of the tail 

 in the female are greatly elongated and multi-ramose, 

 resembling pieces of coral. 



The male is minute, resembling those of the Bopyri, with 

 the head distinct, the outer antennae prominently project- 

 ing beyond the front margin of the head, the inner pair 

 rudimentary, the seven segments of the body of nearly 

 equal size and width (except the first, which is shorter 

 than the rest) ; they are separated from each other by a 

 considerable space, having the lateral margins somewhat 

 angularly produced, the legs being affixed beneath the 

 lateral angles. The legs resemble those of the male 

 Bopyri, and are terminated by a small oval hand, with a 

 small curved finger. The tail is narrower than the hinder 

 segments of the body, and consists of six distinct seg- 

 ments, gradually narrowing in size, each segment being 

 furnished with a pair of elongated slender, cylindrical, 

 membranous appendages (pleopoda). 



The female is much larger than the male, with the 

 body flattened, pear-shaped, and slightly unsymmetrical. 

 The head is transverse in front, its posterior portion being 



