324 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



the group upon a morphological basis. As will be seen the structure 

 in a few instances supports the suggestions that have been made 

 regarding the identity of sexes, while in the great majority of cases it 

 is directly opposed to them. It is obvious, however, that any sugges- 

 tion of species identity which is not supported, or which may even be 

 contradicted by the anatomy of the two sexes, is worthy of very little 

 consideration. 



And it is really surprising how much similarity a careful examination 

 reveals when we remember that the two sexes have been considered 

 generically distinct. The differences are found to be much more 

 apparent than real, and this is particularly true of the appendages 

 which afford a ready clew for the determination of the genera, as can 

 be seen from the key which follows (p. 345). 



There is of course no expectation of being able, in this initiatory 

 effort, to reach a final conclusion respecting all the Nogaus species. 

 Considerable additional information will be needed before that 

 becomes even possible. But at least a good beginning can be made, 

 and the treatment of the species can be placed upon a rational and 

 scientific basis, which will yield good results in the future. 



Each male has been included in the genus to which it belongs, so far 

 as this is positively known, and its characteristics have been given 

 under the genus diagnosis. 



There are here described twenty species, of which one is new to 

 science, namely, EcJdhrdgaleus tor'pedinis , while two others, Echthro- 

 galeus denticulatus Smith and Nesipp^is alatus Wilson, are figured for 

 the first time, the latter including both sexes. 



In addition the males of eight of the other species have been 

 definitely located, described, and figured, four of them being new to 

 science, while the other four have been boarding around among the 

 various genera as w^as formerly the custom with the teachers in our 

 old-fashioned country schools. 



The males of the three species belonging to the Cecropinse, of 

 Gangliopus pyrnformis, and of Pandarus hicolor were already known 

 so that we now have the males of 14 of the 20 species, including at 

 least one for every genus. 



And lastly, much the hardest task of all, in the discussion of the 

 genus Nogaus, which is made up entirely of males, 34 species, 

 described by half as many authors and in seven different languages, 

 have l^een carefully contrasted with one another and with the types 

 here established, so far as the data given made this possible. 



It has been found necessary to change the names of two genera on 

 account of preoccupation. The name Lepidopus, proposed by Dana in 

 1852, had been used by Gouan for a fish genus in 1770. In its place is 

 suggested the name Pliolidopus which has the same meaning, namely, 

 scale-footed. 



