580 CALIFORNIA ACADEMY OF SCIENCES. 



in a few species only, far apart in the series, they must be 

 regarded as sporadic ; thus nuchal spines are present in 

 S. levis, chlorostictiis, aurora and constellatus (in the last 

 species connected with a tendency of the ridges to break 

 up into spines and tubercles), but they are inconstant 

 even in the species in which they occur; so that it is 

 doubtful whether they are always present m any species. 

 The coronal spines, likewise inconstant, are usually pres- 

 ent in S . aurora, and nearly always present in S . auricii- 

 laius. 



In some species in which pairs of spines are normall}^ 

 absent, these are sometimes present in a rudimentary or 

 distorted form, either singly or in pairs. Although the 

 J>aucispinis group is characterized by the absence of the 

 usual pairs of spines in adults, two ^du\i paiicispinis skulls 

 had a rudimentary supra- or postocular on the left side, and 

 a very young skull of this division had rudimentary tym- 

 panic spines on both sides and a postocular on the left 

 side ; a medium-sized niclanops had a rudimentary right 

 tympanic ; and a large one had a pair of postoculars and 

 a deformed left supraocular; a young Jiavidus had a 

 rudimentary right postocular; in an elongatus, in which 

 the supraoculars are normally absent, the spines were 

 still present in the form of low humps on the ridge; in 

 another specimen the supraocular spine was sharp and 

 perfectly distinct. 



Hilgendorf expressed the belief that when one of the 

 three pairs of spines (supraocular, postocular and tym- 

 panic) is absent, it is the supraocular and not the post- 

 ocular that has disappeared.* This is proved by several 



* Hilgendorf : Uebersicht iiber die japauischen Sebastes-Arten, Sitzungs- 

 Bericht der Gesellscliaft Naturforschenden Fi'eunde zn Berlin, 21. Dec, 

 1880, p. 168. "Das maximum von Dornen am Oberkopf kommt bei »S'. 

 onarmoratus vor, niimlich einer in der Nasengegeud, der nasaldorn, drei 

 auf dem Augeurand, Oi-bital-dornen, von denen der mittlere bei den andern 

 Arten zuerst versclivs^indet." 



