NO. 1573. PARASITIC COPEPODS— WILSON. 445 



Pandarus was established three years previously by the same author, 

 and hence the genus name Nogaiis becomes a synonym of Pandarus 

 and must l)e dropped. 



Such being the condition, it becomes necessary to assort the various 

 Nogaus species and connect them as the male sex with the proper 

 females described in other genera. Several efforts have already been 

 made in this direction, but there has been such an utter abandon of 

 even the simplest rules of systematization that it would be deplorable 

 if it were not so ridiculous. 



With one or two exceptions, the only reason which an author has 

 offered for considering a Nogaus form as the male of any species has 

 been the simple fact that it was found with the female of that species 

 upon the same lish. And some have not even taken the trouble to 

 go thus far, but have considered a similarity of geographical distri- 

 bution sufficient evidence of probable identit}^ in the two sexes. 



Geographical distribution certainly counts for something, and the 

 fijiding of the two sexes upon the same fish counts for more, but 

 neither of them has any weight at all when compared with morpho- 

 logical details, except in confirmation of the latter. 



And yet these morphological details are the very things which 

 have been most neglected. In the preparation of the ])resent paper 

 the author has had occasion to examine in minute detail the various 

 genera which compose the subfamily Pandarina;. 



And along with the others came an extended study of this group 

 known as the genus " Nogagus." An earnest endeavor has been 

 made to separate these forms upon a morphological basis, and to 

 connect each of the types with the genus which is its morphological 

 counterpart. In tliiseft'ort the author has* been greatly assisted by 

 the fact that he has himself taken three of the types in actual copu- 

 lation with females of as many different genera. And about the 

 same number have been recorded l)y other writers who have dealt 

 with the Pandarinas. 



The parts of special importance in comparing the various s])ecies 

 are the second maxillae, the second maxillipeds, the rami of the 

 swimming legs, the relative size and shape of the genital segment 

 and abdomen, and the ])resence or absence of the fifth .and sixth 

 pairs of legs and of the lens-like protrusions called by Dana (1852) 

 ''conspicilla" on the dorsal surface of the carapace. 



Using these morphological details as a basis of comparison, we may 

 separate the Nogaus forms into the following genus types: 



Genus Pandarus. — Carapace broad and well rounded, without con- 

 spicilla, but w^ith accessory posterior lobes; genital segment enlarged, 

 showing both the fifth and sixth legs; abdomen two-jointed, joints 

 about the same size; legs all biramose, rami two-jointed; second 



