GREGORY: FISH SKULLS 



327 



them in with the maxillary processes of the palatines, the anterior horns of the mesethmoid 

 and the ascending processes of the suborbital stays. 



Six stages (Fig. 204) in the development of the rosefish {Sebastes marinus) are figured 

 by Bigelow and Welsh (1925, pp. 311, 305). As is usual among teleosts, the eyes are very 

 large in the late embryos, larvae and fry, the brain swells dorsally, the mouth and jaws are 

 at first very small. The body as a whole is elongate and slender, the myomeres forming a 



sphot f^o 



Fig. 205. Purois. Fish from photograph of specimen in action, published by Breder. 



narrow strip along the flanks. As the fry become larger the body deepens rapidly, carrying 

 with it the posterior part of the head; the eye becomes relatively smaller, the jaws longer. 

 Spikes appear on the preopercular rim in the late larval stage. Thus, as in other teleosts, 

 the shape of the head changes profoundly during late larval and young stages. Crests and 

 ridges do not appear until the related muscles are well developed; vertical growth of the 

 occiput waits for the deepening of the back. The dependence of adult skull-form upon 

 body-form could hardly be better illustrated. 



The mail-cheeked fishes are such an extensive group that a detailed review of their cra- 

 nial osteology would unduly expand the present paper. I shall try nevertheless to sketch 

 some of their main specializations, referring the reader for details to the monograph by Allis, 

 to Jordan and Evermann's "Fishes of North and Middle America" and similar sources. 

 With regard to general features the bass-like Sebastes and Sebastodes seem to stand near 

 the ancestral stock, which early divided into several main branches. First, within the 

 family Scorpaenidae many variations on the main theme were played. For example, in 



