2084 Bulletin ^7, United States National Museum, 



2426. XEtfOCHIRUS TRIACANTHUS/ Gilbert. 



B. 6; 1 D. 5 or 6; 2 D.6 or 7; A.6; P.13; V.3(I,2); C. 1-11-1. Body 

 depressed throughout its length, sharply octagonal, peduncle hexagonal ; 

 the sharp, delicate spines present on all the ridges from head to caudal, 

 except the first few plates on the inferior lateral, and on the ventrolateral 

 from a short distance in front of anal to caudal ; one pair of plates between 

 last ray of second dorsal and first median plate (the first 3 median plates 

 sometimes each with a pair of closely approximated spines) and 1 pair 

 between last anal ray and first median plate; about 25 radially striated 

 plates on breast, 5 or 6 small ones on posterior part of gill membranes in 

 front of breast, 1 on each side anteriorly, and 3 or 4 well-developed plates 

 on front part of under side of mandible ; intervals between ventrolateral 

 behind vent with 12 to 15 small plates, mostly in pairs, none between 

 ventrals and vent. Head more depressed and elongate than in X. pentacan- 

 thus and latifrons, its depth in width, the latter 8f in length of body; 

 snout elongate triangular, nearly equal to long diameter of orbit. Orbits 

 oval, the vertical f of the longitudinal diameter, the latter 3 in head; a 

 slightly curved row of 3 to 5 spines on eyeball above pupil. Interorbital 

 space narrow, concave, without minor ridges, 9 in head. Supraocular 

 ridges ending in a sharp spine ; occipital low, with 2 pairs of spines, of 

 which the anterior is low and blunt. Temporal moderate, ending in a 

 sharp suprascapular spine ; suborbital ridge moderate, close under orbit, 

 with 1 spine on suborbital and ending in 1 at edge of preopercle ; below the 

 latter spine, another, broadly triangular; 3 or 4 well-developed spineless 

 plates on lower part of cheek, which enters into ventral surface of head; 

 nasal spines strong, sharp, far apart; median rostral plate small, movable, 

 slightly overhanging, premaxillary (its lateral expansions as free spines) 

 bearing a single upright spine; lower jaw a little included, maxillary not 

 reaching orbit. Barbels probably varying much, for they differ markedly 

 on the 2 sides of the jaw in the single specimen examined. Dorsals well 

 separated; anal beginning about 1 plate behind the beginning of second 

 dorsal; pectorals 5| in length of body, their base -^ of their length, with 

 13 rays, the 4 lower exserted, separated from the rest by a notch, the 2 

 upper of these 4 longer than any of the other rays; ventrals of male 2J 

 in head (in female probably shorter) ; width of caudal at |)ase 2^ in its 

 length. Color olivaceous, with traces of darker cross bars on back, fins 

 light or somewhat dusky, rays dark ; ventrals pale in both sexes. Descrip- 

 tion taken from Dr. Gilbert's type. Total length reaches 7 inches. Coast 

 of California to coast of Oregon, in 47 to 204 fathoms; a specimen also 

 taken off Point Reyes in 75 fathoms. (rp?, three; anarBa, spine.) 



Xenochirus triacanthus, GILBERT, Proc.U. S. Nat. Mas. 1890, 91, coast of California, at Alba- 

 tross Station 2893, in 145 fathoms; JORDAN <fc STARRS, Proc. Cal. Ac. Sci. 1895, 827, pi. 93. 



* Diagnosis : Body tapering uniformly from head to caudal, its depth of width at hase 

 of pectorals, the latter 8| in length; head 5 or a little less. Plates in dorsal series 39; 

 between occiput and first dorsal 7 ; between dorsals 5 ; between ventrals and anal 15 pairs. 

 Two barbels at tip of each maxillary, 1 pair at edge of the terminal mucous pore on under 

 side of mandible, 1 at edge of next pore, and 1 at edge of third pore. Median rostral plate 

 with a single upright spine. Nasal spines prominent; 1 pair supraocular and 2 pairs 

 occipital spines. Teeth on jaws, vomer, and palatines. Gill membranes joined to isth- 

 mus, without free fold. Olivaceous, with traces of darker cross bars ; fins light, the rays 

 darker. 



