26 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63 



XYSTREURYS RIBEIROI, new species. 



Head 3f ; depth, 2^; D. 77; A. 57; P. i, 9; V. i, 5; about 92 

 tubes in lateral line to caudal base ; scales 103 in lateral line to caudal 

 base; 36 scales above lateral line, 40 below; longest dorsal ray 2^ in 

 head; longest anal ray 2^; least depth of caudal peduncle 2f ; right 

 pectoral 3; left pectoral 2^; caudal 1;^; head width 4|; snout 4^ in 

 head, from upper jaw tip to upper eye; upper eye 6^; maxillary 2i\v. 



Body strongly compressed, contour ellipsoid or greatest depth 

 median in its length. Caudal peduncle strongly compressed, length 

 about two-fifths its least depth. 



Head greatly compressed, upper profile slightly concave above eye. 

 Snout convex over surface and in profile, length 1^ its width. Lower 

 eye but slightly advanced from upper, hind edge about first two- 

 fifths in head. Maxillary very oblique, reaches opposite hind pupil 

 edge; expansion 1^ in lower eye. Mouth large, gape curved, and 

 lower jaw well protruded. Row of strong conic teeth in each jaw, 

 several anteriorly largest and little canine like; no teeth on mouth 

 roof. Front (left) nostril at last two-fifths in snout; hind one well 

 separated, opposite front eye edge. Interorbital narrow, width half 

 upper eye diameter. 



Gill-opening forward about opposite hind pupil edge. Gill-rakers 

 3+15, lanceolate, 1^ in filaments, which are 1| in eye. Pseudo- 

 branchiae two-thirds of gill-filaments. 



Scales in rather even longitudinal rows. Dorsal, anal, pectoral 

 and ventral scaleless, and caudal largely covered with small scales. 

 Head, except jaws and snout, scaly. Cheek with 14 rows of scales 

 from lower eye edge to angle of preopercle ridge. Maxillary scaly. 

 Scales cycloid ; basal radiating striae 24 or 25 on left or colored side, 

 and 20 or 21 on blind side ; lateral line begins below lower eye, then 

 curves upward and back to shoulder on head; arch 3f in straight 

 section; moderate tubes simple. 



Dorsal begins on snout, opposite front of lower eye. Anal begins 

 opposite pectoral origin. Caudal with median rays longest, forming 

 median obtuse point behind. Pectoral small, pointed. Ventral in- 

 serted about opposite hind preopercle edge. 



Color in alcohol mummy-brown on left side, and fins similar. 

 Right side paler to olive-gray. 



Length 202 mm. 



Typc.—Q^t. No. 83404, U.S.N.M., Rio Janeiro. Wilkes Exploring 

 Expedition. 



Also Cat. No. 83399, U.S.N.M. No locality, though doubtless from 

 Rio Janeiro. Wilkes Exploring Expedition. It shows: Head 3^; 

 depth 1^; D. 76; A. 54; scales 102 in lateral line to caudal base; 

 about 95 tubes in lateral line to caudal base; 32 scales above lateral 



