Jordan and Evcrmann. — Fishes of North America. 17G9 



directed upward; the ventral process of the basisphenoid is abseut, or 

 reduced to a mere point, or at most occasionally present in very young 

 specimens; the cranial ridges are poorly or not at all developed, and the 

 spines are delicate or absent. In the rosaceus-nehulosus groups the base of 

 the skull is straight or nearly so; the interorbital space is always concave 

 and narrow, its ratio in the base of the skull varying from 4^ to 6*; the 

 mesethmoid jjrocesses are always directed more or less upward; and the 

 ventral process of the basisphenoid, the cranial ridges and the spines are 

 strongly developed. 



These 2 groups of characters would furnish an ample basis for the 

 division of the genus into 2, if the species mentioned were alone to be 

 considered. But between the 2 groups distinguished by these characters 

 lies another {introniyer-aurora) in which the base of the skull is somewhat 

 curved (approaching straightness), the interorbital space is Hat or slightly 

 concave, of medium width, 4 to ii into the base of the skull, the processes 

 of the mesethmoid are directed but little upward and the ventral process 

 of the basisphenoid is poorly developed. By the interi^osition of this 

 group it is jjossible to arrange a series i'Tom2)aucispinis to rosaceus in Avhich 

 there is an almost perlect gradation of all the above-mentioned characters, 

 from strikingly curved to straight base of skull, from convex and broad to 

 concave and narrow interorbital space, from mesethmoid processes de- 

 pressed to those directed 45" above the dorsal plane of the skull, from a 

 rudimentary to a fully developed ventral process of the basisphenoid, and 

 from nearly obsolete to strongly developed cranial ridges. 



The single species ruberrimua furnishes at different stages in its develop- 

 ment a series of characters that parallel in a striking way the series just 

 described. The very young skull is so much like those of rosaceus and 

 rhodochloris that, if it were the only ruberrimns at hand, it might easily be 

 put between them in a series. The width of the interorbital space is 6-| into 

 the base of the skull, relatively narrower than that of any other skull in 

 the collection of 50, and deeply concave; the mesethmoid processes are 

 directed upward and the ventral process of the basisphenoid is well devel- 

 oped. The very large skull of the same species is almost exactly adapted 

 to the description of the aurora-'mtronhjer grouj). The interorbital si^aco 

 is perfectly flat and 4^ into the base of the skull, the mesethmoid proc- 

 esses extend forward nearly horizontally and the ventral jirocess of the 

 basisphenoid is rudimentary. The gap between these two extremes is 

 completely closed by skulls of intermediate age. 



S. saxicoJa and diploproa constitute another intermediate group with the 

 base of the skull markedly curved, the interorbital space slightly convex 

 or flat, of medium width, 3| to 4:^ into the base of the skull, mesethmoid 

 pi-ocesses directed but little upward, and the ventral process of the basi- 

 sphenoid rudimentary or fairly developed. This intermediate group, unlike 

 the other, lacks the supraocular spine and probably forms one of the links 

 between the cntomelas-pinniger group and the other rockfish in which the 

 supraocular is wanting. 



The following classification (containing most, but not all, of the species), 

 3030 34 



