NATURAL SCIENCES OP PHILADELPHIA. 59 



transversely triangular, scarcely sinuous behind and uniformly high, with its 

 ends scarcely curved backwards to its posterior facettes, which are narrow, 

 little prominent above and separated from the dentigerous area by a con- 

 traction ; the shaft is laminar, expanded obliquely downwards and forwards. 

 The teeth on the body are nearly uniform, moderate, and paved, and on the 

 crest of the shaft obtusely cylindro-conic. The upper pharyngeal bones are 

 high, curved in front, on which is a tessellated pavement and which is nearly 

 rectangular to the inferior surface, which is paved towards the inner side with 

 moderate and towards the outer with minute teeth. 



The gill rakers on the outer surface of the first branchial arch are 

 short compressed, parallel with the arch, bi- or multidentate ; the others are 

 oblique and more or less compressed at right angle to the arches. 



Type Pimelometopon pulcher Gill. 



This genus is very closely related to Trochocopus (Giinther), but differs in 

 the possession of a greater number of scales and the form of the head. It is 

 also solely represented by species found along the western coasts of America 

 and the appertaining islands, while Trochocopus is a peculiar African type, 

 so far as yet known. 



Of the two known species of this genus, one the type was originally 

 described as a Labrus by Ayres in San Francisco ; the other was first made 

 known by Jenyns under the generic name Cossyphus and was afterwards, by 

 Valenciennes, described as a new species of Labrus. Dr. Giinther subse- 

 quently referred the Californian species to his genus Semicossyphus and the 

 species of Jenyns and Valenciennes to Trochocopus; he was acquainted 

 with neither through autopsy. Finally, the writer, following Giinther and 

 unacquainted with either Semicossyphus or Trochocopus, retained the Cali- 

 fornian species in the former genus. 



Pimclomotopon belongs to the subfamily of Chccropinse as understood by 

 me. It is proper to here remark that, by an evident inadvertence, the sub- 

 family Pseudolabriformes of Bleeker was formerly* enumerated among those 

 considered valid by myself, instead of among those requiring revision. 



There are two known species of the genus Pimelometopon: 



Pimelometopon pulcher Gill = Labrus pulcher Ayres Semicossyphus 

 pulcher Giinther, Gill. 



California. 



Pimelometopon Darwinii Gill = Cossyphus Darwinii Jenyns = Labrus 

 aper Val. 



Gallopagos Islands. 



N. B. In anticipation of a special paper, I may here state that the Sebastes! 

 helvomaculatus of Ayres is the true Sebastes rosaceus of Girard, (Sebastomusf ro- 

 saceus Gill,) widely different from the Sebastodes ! rosaceus of Ayres. The latter 

 may be named Sebaslosomus pinniger. 



Note on the Nomenclature of Genera and Species of the Family 

 ECHENEIDOIDJE. 



BY THEODORE GILL. 



In order to correct the nomenclature of two of the genera of the family 

 Echeneidoidse, the following paper is submitted. I also embrace the oppor- 

 tunity of restoring to proper rank, as the true names of peculiar species, two 

 which have been connected with forms to which they do not truly belong. 



M. Auguste Dumeril, in a "Prodrome" of a projected Monograph of the 



family, (Comptes Rendus, tome 47, 1858, pp. 374 378,) has proposed to 



distribute the species among two groups, one typified by Echeneis nnicrates, 



and named Nancrates, and the other, represented by E. remora and called 



Remores. Elevating these types with others to independent generic rank, I 



* Proc. A. N. S. 1833, p. 221. 



f Sebastosomus, n. g. Type Sebastosomus melanops = Sebastes melanops Girard. 



1861.] 



