2786 Bulletin ^7, United States National Museum. 



anteriorly, as in other species of Tacliysnrns; profile rising in a uniform, 

 gently convex curve to occiput, where it becomes concave, owing to the 

 more rapidly ascending outline of the occipital process. Eye low, but 

 little above angle of mouth, the interorbital space decidedly convex. 

 Barbels slender, the maxillary barbels reaching edge of gill membrane in 

 front of pectoral spine, the outer mental barbels extending beyond gill 

 membrane, li in head, the inner not to edge of membrane. Gill mem- 

 brane widely attached to isthmus, without free edge. Occipital region 

 with very fine granulations, those on middle of occiput forming parallel 

 series aloug the fontanel groove, those on median portion of occipital 

 process in series which diverge backward from the median line. The 

 sculptured area extends forward to a vertical wliich traverses the cheek 

 at a distance of its own diameter behind the eye; anterior edge of granu- 

 lated area equidistant between tip of snout and front of dorsal plate; 

 fcmtanel produced backward as a deep, narrow groove, which fails to 

 reach base of occipital process by a distance equaling k the length of the 

 process on the median line; the groove widening but little anteriorly; 

 an area behind and on each side of the groove with parallel series of 

 granulations, and marked off from the rest of the head by a shallow 

 trench; base of occipital process similarly indicated by a transverse 

 indented line; occipital process not keeled, very wide at base, becoming 

 abruptly very narrow behind, its posterior \ having parallel margins 

 and being as wide as long, the lateral margins therefore deeply concave; 

 width of process at base eiiualing its length on median line, jjIus that 

 of dorsal plate, its hinder edge dcejily incised to receive the anterior 

 rounded wedge process of the dorsal plate, the latter finely granulated 

 anteriorly, the lateral wings concealed under the smooth skin; a nar- 

 row groove as long as eye occupies the anterior end of tlie fontanel; 

 no similar groove found in T. fiirthii, a short roundish one present in the 

 type of T. liropus, and a continuous one the entire length of fontanel in 

 the specimen which we identify with 'T.melanopus ; opercle without radia- 

 ting ridges; a short, slit-like axillary pore present; humeral process 

 short, the exposed portion not broadly triangular, the surface smooth, or 

 indistinctly rough. Gill rakers 6-f-13, of moderate length and thickness, 

 the longest below the angle, g diameter of eye. Dorsal spine with a series 

 of obtuse granulations in front and very weak retrorse serr;e- behind, its 

 length to tiji of calcified portion 1? in head; longest soft ray I5 in head; 

 adipose dorsal not adnate, its anterior insertion about over middle of anal; 

 distance between dorsals ecfual to length of head ; base of adipose dorsal 

 much greater than its height, less than base of iirst dorsal; pectoral spine 

 strong, ridged and granulated in front, the hinder edge with very strong 

 serra-; length of spine If in head, the fin projecting beyond tip of spine 

 and reaching | distance from axil to base of ventrals; ventrals reaching 

 to or nearly to origin of anal; vent midway between base of ventrals and 

 front of anal; base of anal ('(jualing length of pectoral spine; margin of 

 anal gently concave, the longest ray 2 J in head; caudal with ])Ointed 

 lobes, the lower longest in the type. 1^ in head Color dark steel blue or 

 brownish above, becoming bright silvery below; posterior f of anal white 



