()(U PROCEEDINGS OF THE NATIONAL MUSEUM. voi.. xxvin. 



posteriorly, with almost straight sides. It is only one-fonrth as wide 

 as the carapace, about as wide as h)ng, and carries two pairs of papilln? — 

 one on the lateral margin and the other at the posterior corners, the 

 two close together. 



The first pair, on the lateral margins, represent the fifth legs and 

 are much better developed than in an}^ species of Caligus or Lepeoph- 

 theirus thus far observed. On the ventral surface in favorable speci- 

 mens this pair of legs may be traced to the very })ase of the genital 

 segment; and the}' also show an indistinct segmentation, which is very 

 unusual. 



The second pair represent the sixth legs, and are in the condition 

 usually assumed by the fifth pair, except that the}^ show only two 

 spines instead of three. 



As in the female, the dorsal surface of this segment is covered with 

 a lamina which projects over either lateral margin and covers the 

 bases of the fifth legs posteriorly. 



The abdomen is very short, scarcely reaching l)eyond the tips of the 

 fifth-leg papillae, and is wider than it is long, with very large anal 

 lamina', armed with long and stout seta. 



The first antenna are large and project well beyond the lateral mar- 

 gins of the carapace. The second pair are also enlarged, as usual in 

 this sex, and well branched. 



The second maxillipeds are enlarged rather more than usual, and 

 must form powerful prehensile organs. 



The basal lamina, or apron of the third legs, are very large and 

 reach back fully to the center of the genital segment. Being plenti- 

 fully supplied with powerful muscles, they form a swimming organ of 

 great strength, and nmst propel the animal through the water swiftly. 

 They must also be equall}^ efi:'ective in the prevention of slipping. 



The fourth legs are much enlarged and so long that they reach well 

 beyond the tips of the plumose seta on the anal lamina. The basal 

 joint on each of them is as large as the entire free segment. They are 

 armed, as in the female. 



Total length 2.5 mm. Length of carapace 1.8 mm.; width of same 

 2 mm.; length of genital segment 0.35 nmi.; length of the fourth legs 

 1.5 mm. 



The National Museum collection includes a single lot of this inter- 

 esting species; it is luunbered W. 75, and was taken from the ))lue cod, 

 Opldodon ehmgatus^ locality unknown. 



Its chief interest lies in the fact that it forms a connecting link 

 between the subfamily Caligina, which is here treated, and that of the 

 Eur3'phorina, their nearest relatives. 



By reference to the key on page 532 it will be seen that the Caligina 

 are characterized by the entire absence of dorsal plates or appendages 

 on the fourth segment of the thorax, with the exception of the fourth 



