4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lie 



which the reader is referred.^ Grammonoides is also different in 

 dentition, lacking the bands of granular teeth on the premaxillary 

 and the dentary. 



Among the genera confined to deeper water, the closest relatives 

 of Oligojms are those forms with a tubular anterior nostril placed 

 directly over the upper lip, reduced squamation on the head, and a 

 single ray in each ventral fin. This group includes Diplacanthoyoma, 

 Myxocephalus, the species presently assigned to Cataetyx (at least 

 two genera are included in this group), and Bythites. All of these 

 differ from Oligopus in possessing palatine teeth, and in lacking 

 shortened, truncate neural spines. In addition, Diplacanthopoma 

 and Myxocephalus lack scales on the head. Most of the species of 

 Cataetyx (though not the type, C. messieri) have strongly depressed 

 heads. 



Oligopus ater, the type species of Oligopus, long has been considered 

 congeneric with a superficially similar species that was described 

 originally by Doderlein (1886) as Pteridium armatum. Bougis and 

 Ruivo (1954) reported on specimens that they identified as Ben- 

 thocometes robustus, a name that they treated as a senior synonym of 

 P. armatum. They illustrated (their fig. 19) specializations of the 

 anterior vertebrae that bear some resemblance to those long known 

 to exist in the Ophidiidae (in the restricted sense), but there is some 

 conflictin this identification, for Doderlein (1886) did not show modified 

 anterior vertebrae in his figure of a dissection of Pteridium armatum. 

 These structures, however, have been shown to be sexually dimorphic 

 in the ophidiid genus Ophidion (Rose, 1961). Whatever the identity 

 of P. armatum, Oligopus differs widely both from Doderlein's descrip- 

 tion and from Benthoco metes. It is of interest to note that another 

 species of Oligopus (0. claudei) was also confused with Benthocometes. 



The foregoing discussion is based on the material listed below. 



Material examined. — Benthocometes robustus (USNM 29057, 

 paratype) ; Bythites juscus (UCZM, holotype) ; Bythites lepidogenys 

 (USNM 74152, holotype); Cataetyx hawaiiensis (USNM 162715, 

 holotype) ; Cataetyx laticeps (UBZM, holotype) ; Cataetyx messieri 

 (BMNH, holotype) ; Diplacanthopoma brachysoma (BMNH, holotype) ; 

 Diplacanthopoma brunnea (USNM 74148, holotype); Grammonoides 

 opisthodon (RU, holotype); Microbrofula rubra (USNM 162710, 

 holotype); Myxocephalus japonicu^ (USNM 160604); Stygnobrotula 

 latebricola (USNM 187777); Xenobythites armiger (USNM 74153, 

 holotype). 



Synonymy. — In his original description of Oligopus ater, Risso 

 (1810) credited the genus Oligopus to Lacepede; however, Risso's 



2 Boeseman (1960) overlooked the description of Stygnobrotula latebricola and 

 described the same species as Eutyx tumidirostris. 



