364 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Gill-openings very wide, tlie branchiostegal membranes little united, 

 leaving- nearly all of isthmus uncovered ; the membranes united as far 

 back, only as vertical from end of maxillary. Opercle adherent above 

 the upper angle, which is produced in a point extending above the base 

 of pectorals. Below the angle the opercular margin runs very obliquely 

 forwards. Eye large, equaling length of snout, greater than interor 

 bital width. 



Origin of dorsal fin distant from nape by the length of the head ; the 

 fin a very inconspicuous fold anteriorly, becoming higher posteriorly, 

 where the rays are evident. Anal well developed along entire length, 

 beginning immediately behind vent and running to tail ; its rays visible. 

 Caudal exceedingly short. Pectorals very well developed, more than 

 half length of head. Vent just in front of base of pectorals. 



Head 6^ in length; depth 10 J; eye 5 in head. 



Head and body perfectly translucent ; a faint silvery luster on middle 

 of sides anteriorly ; a few inconspicuous small light yellowish spots along 

 middle of sides (disappearing in alcohol) ; tip of tail dusky; upper margin 

 of orbit black. 



A single specimen, 3^ inches long, was found buried in the sand at 

 tow-tide on the beach of Mazatlan. 



32. Etropus crossotus, gen. and sp. nov. (Pleuronectidce.) (28124.) 



Char. gen. — Byes and color on the left side. Body deep, regularly 

 oval. Head small ; mouth very small, the teeth close set, pointed, in a 

 single series, mostly on the blind side. Eyes narrow, separated by a 

 narrow scaleless ridge. Margin of preopercle free. Ventrals free from 

 the anal, that of colored side on ridge of abdomen. Dorsal beginniug 

 above eye; caudal fin double truncate; anal fin not preceded by a spine; 

 scales thin, ctenoid on left side, smooth on blind side; lateral line sim- 

 ple, nearly straight, {erpov, abdomen; -ou<;, foot; the ventral being on 

 the ridge of the abdomen.) 



Char, spec— Body oval, strongly compressed, with the dorsal and 

 ventral curves nearly equal ; both outlines strongly arched anteriorly. 

 Head very small; suout short; mouth very small, its cleft not so long 

 as the diameter of the orbit. Teeth conical, pointed, close-set, strongly 

 incurved, in a single series. Those in the upper jaw on the blind side 

 only; those in the lower jaw, on both sides. Eyes large, the lower in 

 advance of the upper, the two separated by a very narrow scaleless 

 ridge, which extends backward above the preopercle. Edge of opercle 

 on the blind side, with a row of conspicuous white cilise. Upper nostril 

 turned somewhat to blind side; anterior nostril of left side, with a very 

 slender cirrus. 



Dorsal fin commencing over front of upper eye, its middle rays high- 

 est, the anterior not elevated. Anal fin not preceded by a spine, its 

 middle rays highest. Caudal fin very sharply double-truncate ; as long 

 as head. Pectorals short, that of left side the longer, about three- 



