A KEVIEW OF THE FLOUNDERS AND SOLES OF JAPAN. 



By David Starr Jordan and Edwin Chapin Starks, 



Of Stanford Uidirrsit)/, California. 



In this paper is g-iven a descriptive catalogue of the species of the 

 families Fleuronectidse and Soleidffi, tiounders and soles, known to 

 inhabit the waters of Japan and the shores of the Japan Sea. It is 

 based primarily on the collection made by Professors Jordan and 

 Snyder in the summer of 1900. Series of these specimens are in the 

 United States National Museum, in the British Museum, and in the 

 museum of Stanford University. The new illustrative figures are the 

 work of Mrs. Chloe Leslie Starks and Mr. William S. Atkinson. 



The flounders and soles together constitute the suborder Hetero- 

 somata. The relations of this group are uncei'tain, but it is evident 

 that these fishes have no special affinity with the Gadidse or with 

 other forms with jugular ventral fins. Boulenger associates the floun- 

 ders with the Zeid», and suggests the derivation of both groups from 

 the extinct family Amphistiidte. But there is no positive warrant for 

 this ingenious guess. 



Suborder HETEROSOMATA. 

 FLATFISHES. 



Cranium posteriorly normal; anteriorly with twisted vertex, to 

 allow two orbits on the same side of the head; basis cranii not quite 

 simple; dorsal fin long, of jointed rays; superior pharyngeals 4, the 

 third longest, much extended forward, the inferior separate; ventral 

 fins thoracic rarely wanting; of more than five rays, all articulate; no 

 fin-spines; shoulder-girdle normal, the hypercoracoid perforate. In 

 the very young fishes the two sides of the body are alike and the eyes 

 are one on each side, with normal cranium. 



KEY TO FAMILIES OP HETEROSOMATA. 



o. Preopercular margin more or less distinct, not hidden by the skin and scales of 

 the head; eyes large, well separated; mouth moderate or large; teeth present. 



Pleuronectid.e, I 



(la. Preopercular margin adnate, hidden by the skin and scales of the head; eyes 

 small, close together; mouth very small, much twisted; teeth rudimentary or 

 wanting. ' Soleid^, II 



Proceedings U. S. National Museum, Vol. XXXI— No. 1484. 



161 



