7 GENUS SEBASTODES. 575 



In 1864 Gill 3 separated the then known rock-fishes of 

 the Pacific Coast into four genera : Sebastodes, Sebas- 

 tickthys, Sebastosomus and Sebastomus. The groups which 

 he thus indicated form natural assemblages of species, 

 but thus far he has never defined them satisfactorily. 

 The genera proposed by him have generally been accepted 

 as of subgeneric value by later workers in the group, but 

 with a knowledge of the early known species which Gill 

 was unable to examine, together with many others discov- 

 ered since, they have found it impossible to draw the lines 

 of generic separation indicated by him. 



In 1880 Jordan and Gilbert 4 discovered and described 

 fifteen or more new species, and adopted a more definite 

 terminology for the spinous ridges of the cranium, which 

 seemed to them to furnish the most reliable characters. 

 The arrangement adopted by them on the basis of these 

 characters agreed in the main with the generic grouping 

 already proposed by Gill. Since, therefore, the charac- 

 ters furnished by the top of the head had been most re- 

 lied upon for the grouping of the species, and it was still 

 a mooted question whether they should all be included in 

 one genus or distributed among several, it seemed to the 

 writer desirable to make a detailed examination of a 

 series of skulls in order to determine what other cranial 

 characters, if any, were correlated with those of the top 

 of the head, and whether there were any gaps in the 

 series which would serve as points of separation into gen- 

 era. 



As will be seen later, the writer has been unable to dis- 

 cover a basis for such generic separation and is convinced 

 that the cranial characters fail to indicate such. Since 

 the present investigation was completed, however, an at- 



3 Gill: Proc. Acad. Nat. Sci. Phil. 1864, p. 145. 



4 Jordan & Gibert: Proc. U. S. National Museum, 1880, p. 287. 



