640 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Family HOPLICHTHYIIbE. 
Hoplich.th.ys citrinus, new species. Fig. 249. 
Type, a male, 175 mm. long, from Albatross station 3859, Pailolo Channel, depth 138 fathoms; 
No. 51610, U. S. Nat. Mus. 
Very close to H. langsdorfii Cuvier & Valenciennes, from Japan, agreeing with that species in 
general proportions and in number of plates and fin rays. It differs in coloration, in the production 
of larger spinous lobes along lateral contour of head, in certain minor differences in the sculpturing of 
the lateral plates and the bones of the head, and in the shape of the fins. 
Length of head 32 hundreths of total length without caudal; greatest width of head, at base of 
spinous ridges 22; depth of head 9; diameter of orbit 8; interorbital width 1.7; length of snout 11; 
length of maxillary 12; length of first dorsal spine 21; length of second dorsal ray 46; longest pectoral 
ray 22; longest ventral ray 12.5. D. vi-15; A. 17; P. 13 + 3; V. i, 5. Lateral plates 27. 
Head greatly flattened; snout wide, spatulate, its longitudinal profile concave; lateral profile of 
head formed by a sharp dentigerous ridge, divided into 4 well-marked lobes: a preorbital lobe, a short 
lobe below front of eye, a greatly expanded rounded lobe below cheeks, and a fourth lobe constituting 
lower margin of opercle and ending in the very long curved preopercular spine; in H. langsdorfii the 
lobes are much less expanded and convex, this being especially noticeable in the one on the cheeks, 
between which and the preopercular lobe is but an inconspicuous notch. 
Interorbital space very narrow, channeled, the margins minutely denticulate; minutely toothed 
areas and ridges on snout, cheeks, opercular bones, and occiput; these regions somewhat less rough 
Fig. 249 . — Hoplichthys citrinus Gilbert, new species. Type 
than in langsdorfii ana the toothed area on the prefrontal wider; a short series of spinelets on inter- 
opercle, behind angle of mouth, and others on lower side of preorbital; opercle marked by 5 to 8 
rough striae, which diverge from the upper anterior angle; the strongest of these ribs ends in the long 
opercular spine; a short strong humeral spine present; broad bands of minute villiforin teeth on jaws, 
vomer and palatines; lower jaw shorter than upper, everywhere included; maxillary extending back- 
ward to a vertical which intersects orbit midway between front of orbit and front of pupil; gills very 
small, laminae extraordinarily short, scarcely longer than the transverse diameter of gill-arch; a single 
series of filaments on inner arch, which has no slit behind it; 10 or 12 short gill-rakers on horizontal 
limb of outer arch; pseudobranchiae well developed; branchiostegal rays 7, the membranes broadly 
united below to isthmus, without free fold; lower ends of gill openings separated by a distance equal- 
ing 0.15 length of head; by the great production of the opercular flap, the upper end of the gill-slit 
appears as a small round pore on the upper aspect of the greatly flattened head, resembling the 
branchial pore in Callionymus, but this pore is simply the upper end of the wide slit. 
Dorsal fins greatly elevated in the males, as is also the case in H. langsdorfii, but the details in the 
2 species are widely different. In H. citrinus, the first dorsal spine is produced and filamentous, 
sometimes extending well beyond origin of soft dorsal, the upper margin of the fin deeply concave; 
some or all of the first 4 rays of soft dorsal are still more produced and filamentous, one or more of 
them in extreme cases reaching, when declined, beyond base of fin; the succeeding rays are entirely 
