5S0 CALIFORNIA ACADEMY OF SCIENCES. 12 



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

 regarded as sporadic : thus nuchal spines are present in 

 S. levis, chlorostictus , 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 in any species. 

 The coronal spines, likewise inconstant, are usually pres- 

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

 latus. 



In some species in which pairs of spines are normally 

 absent, these are sometimes present in a rudimentary or 

 distorted form, either singly or in pairs. Although the 

 -paucisfiinis group is characterized by the absence of the 

 usual pairs of spines in adults, two adult j>aucisj)inis skulls 

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

 a very 3 r oung skull of this division had rudimentary tym- 

 panic spines on both sides and a postocular on the left 

 side ; a medium-sized me/a/wfls had a rudimentary right 

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

 a deformed left supraocular; a young jlavidus had a 

 rudimentarv right postocular; in an e/ongatits, 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. 



Ililgendorf 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 



* Hilgeudorf : Uebersicht liber die japaniscken Sebastes-Arten, Sitzungs- 

 Bericbt der Gesellschaft Naturforschenden Freunde zu Berlin, 21. Dec, 

 1880, p. 168. "Das maximum von Domen am Oberkopf kommt bei <S'. 

 marmoratu8 vor, namlich einer in der Nasengegeud, der nasaldorn, drei 

 auf dem Augenrand, Orbital-dornen, von denen der inittlere bei den andern 

 Arten zuerst verschwindet." 



