Salmopercas and Other Transitional Groups 247 



We may, however, regard the Zeoidea on the one hand and 

 the Heterosomata on the other as distinct suborders. This is 



FIG. 196. Amphistium paradoxum Agassiz. Upper Eocene, (Supposed ancestor 

 of the flounders). (After Boulenger.) 



certain, that the flounders are descended from spiny-rayed 

 forms and that they have no affinities with the codfishes. 



Amphistiidae. The Amphistiidce, now extinct, are deep-bodied, 

 compressed fishes, with long, continuous dorsal and anal in which 

 a few of the anterior rays are simple, slender spines scarcely 

 differentiated from the soft rays. The form of body and the 

 structure of the fins are essentially as in the flounders, from which 

 they differ chiefly by the symmetry of the head, the eyes being 

 normally placed. Amphistium paradoxum is described by Agas- 

 siz from the upper Eocene. It occurs in Italy and France. 

 In its dorsal and anal fins there are about twenty-two rays, 

 the first three or four undivided. The teeth are minute or 

 absent and there is a high supraoccipital crest. 



The John Dories: Zeidae. The singular family of Zeida, 

 or John Dories, agrees with Chaetodonts in the single char- 

 acter of the fusion of the post-temporal with the skull. The 

 species, however, diverge widely in other regards, and their 

 ventral fins are essentially those of the Berycoids. In all the 

 species there are seven to nine soft rays in the ventral fins, as 

 in the Berycoid fishes. Probably the character of the fused 



