2082 Bidletin //, Lhiitcd States National Museum. 



canihus, but strouger and rougher; 3 or 4 stroug plates present on 

 gular membrane; a few weak ones or none on brancliiostegal membrane 

 mesially. Two barbels at tip of each maxillary, and a pair, often double, 

 on under side of mandible arising from the margin of the anterior pair of 

 mandibular pores. The symphyseal pore has its margin sometimes pro- 

 vided with very short barbel-like elevations. Space between dorsal ridges 

 very deeply concave in front of dorsal fins; the single ridge behind dorsal 

 fins provided with vei-y short, scarcely preceptible, double spines; lower 

 lateral series of plates continued forward to axil of pectorals, becoming 

 indistinct in X. pentacanlhus; ventral series anteriorly with lew short 

 spines or none, this series strongly spined in X. pent acanthus; i)lates on 

 breast arranged alike iu the 2 species, but in X. alascauus they nre more 

 finely striate, and bear neither spines nor raised centers, except in very 

 young examples. In X. pcnfacanthiLs the elevated centers may or may not 

 bear short spines. Seven plates before dorsal, 8 or 9 under spinous dorsal, 

 2 or 3 between dorsals, 7 or 8 under soft dorsal, 13 or 14 behind dorsals. 

 Distance from snout to nape equaling or slightly exceeding that from nape 

 to first dorsal. Front of anal under end of spinous dorsal or slightlj^ 

 behind that point, more anteriorly placed than in X. pent acar> thus. Ven- 

 trals 2^ to 2^ in head. Lower pectoral rays produced, with incised mem- 

 branes as long as head behind rostral spines. Color lighter than in X. 

 pentacanthns, more or less finely speckled above, usually with 5 or 6 dusky 

 cross bars on back; a vseries of linear dark blotches below the lateral line; 

 head often finely speckled with brown, and showing traces of a brown 

 bar forward from eye to snout; dorsals, caudal, and upper half of pec- 

 toral light, finely speckled with brown, the caudal shaded with dusky; 

 ventrals and anal white. Most nearly related to X. penlacanlhus with 

 which it agrees in having a rostral plate bearing 3 spines and in the 

 absence of a free fold to branchiostegal membranes. It difi^"ers conspicu- 

 ously in the broader head, with its much heavier spines and ridges, in the 

 presence of deep j)ostocular and nuchal pits, in the smooth breast and 

 cheeks, in adults in the difterent coloration and fin rays, and in many 

 other difierent details. Aleutian Islands; taken rather abundantly in 

 the vicinity of Unimak Pass, both north and south of the islands, at 

 depths of .56 to 138 fathoms. (Gilbert.) Taken by us off Karluk. {alas- 

 caiius, pertaining to Alaska.) 



XenocMrus alascanus, Gilbert, Eept. TJ. S. Fisb Comm. 1893 (1896), 438, Unimak Pass 

 Aleutian Islands. (Coll. Albatross.) 



2425. XENOCHIKUS LATIFROXS,* Gilbert. 



B. 6; ID. 6 or 7; 2 D. 7; A. 7 or 8; P. 14 or 15; V. 3 (1,2); C. 1-11-1; 

 vertebrae 12 -|- 29 = (41). Body as deep as wide, 8-hedral; caudal pe- 



* Diagnosis: Body slender, tapering uniformly from head to caudal; depth equaling 

 width, the latter at base of pectorals 8J in length ; head 4J. Plates in dorsal series 37 to 

 40; between occiput and first dorsiil 6, occasionally 7: hctwccn dursals 4 or 5; from ven- 

 trals to anal 13 or 14 pairs. One liir,i;c liarlicl at li]) i I iiia \illarv, 1 pair ncai' tip of lower 

 jaw, at edges of terminal iiiiicnus jiore, and 1 ;it vi\'j.r ol iirxl ii(ir<'. Mrdiaii mstral ])late 

 present, with a single npriglit spine. Nasal spines jironiineiit, separated; 1 pair supra- 

 ocular and 2 pairs occipital spines. Teeth in .iiiws, vomer, and palatines. Gill membranes 

 .joined to isthmus, with narrow free fold behind. Dusky olive, paler below; 5 or 6 indis- 

 tinct dark cross bars; spinous dorsal with black margin. 



