676 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
on head low but distinct, the inner pair on occiput converging posteriorly, then again slightly diverg- 
ing. Median rostral ridge inconspicuous; the strong infraorbital ridge ends posteriorly, in a short 
strong spine, beyond which projects the soft membranous margin of the preopercular lobe; upper limb - 
of preopercle gently concave in its lower half, gently convex in the upper; transverse width of mouth 
at tips of maxillaries equal to 0. 6 width of snout at same level ; front of mouth opposite anterior nostril ; 
tip of maxillary reaching a point opposite posterior margin of pupil; length of maxillary 0.7 preoral 
portion of snout; teeth small, in wide bands in each jaw, none of them enlarged; barbel very slender, 
half diameter of pupil; gill-membranes forming a very narrow free fold across throat; 9 tubercles 
represent gill-rakers on outer arch. 
First dorsal fin inserted directly above axil of pectoral; second dorsal spine smooth throughout and 
very slender and weak, the distal half as flexible as a ray, its length equaling 0.7 that of snout; the 
distance between dorsals equals base of anterior dorsal without its spines, and is crossed by 3 series of 
scales; anal originating under second or third ray of second dorsal; inner base of ventrals midway 
between vent and edge of branchial membrane on median line; ventral filament reaching vent; 
pectorals reach to a point opposite origin of anal fin. 
Scales of back and sides each with a median ridge composed of imbricating spines, which increase 
regularly in length posteriorly, the last one projecting little if at all beyond margin of scale; also from 1 
to 6 pairs of similar but very low parallel lateral ridges, which never approximate in size to the central 
ridge, and rarely reach margin of scales; spination- much weaker than in parallelus or aratrum; on 
breast and abdominal regions, the lateral series are much stronger than on back and sides, and are still 
parallel or nearly so; scales on head without spines, but roughened with minute prickles, which are 
arranged in more or less evident radiating or stellate series; a naked area is evident on middle of occiput, 
where the scales fail to meet; naked lines also follow along the ridges, and between nasal bones and 
rostral ridge; nasal fossa nearly as large as pupil; lower side of head wholly naked, except for a small 
patch of prickles near tip of snout; 5 series of scales between lateral line and second dorsal fin; 13 
scales in a series upward and backward from vent to lateral line. 
Color very light gray, all the fins, including ventral filament, black throughout; terminal portion 
of snout and lower side of head blackish; lining of mouth, gill-cavity, and peritoneum black, very 
faintly visible externally. 
In young specimens, 125 mm. long and less, apparently belonging to this species, the scales on 
back and sides are essentially similar to those in adults, both median and lateral series of spines being 
present, and in about the same relative size. The cephalic ridges seem proportionally higher and 
are strongly spinous, including a median rostral ridge which loses its prominence in adults; but the 
intervening areas on head, as well as the breast and belly, are covered with smooth cycloid scales, a 
few only showing a series of median spines. Specimens' less than 100 mm. long are marked by a series 
of 10 to 15 small black spots along base of anal fin. 
Taken at the following stations: Nos. 4021, off the east coast of Kauai, 286 to 399 fathoms; 4109, 
Kaiwi Channel, 442 to' 449 fathoms; 4112, Kaiwi Channel, 433 to 447 fathoms; 4122, off the southwest 
coast of Oahu, 192 to 352 fathoms. 
Mateeocephalus acipenserinus (Gilbert & Cramer). 
A very abundant species at depths between 200 and 400 fathoms. The following details may be 
added to the original description of the species. 
Lateral margins of head angulated at a point immediately in front of nostrils, in front of which the 
contours converge much more rapidly. In this anterior segment of the snout, the lateral margin is soft 
and membranous, with skeletal basis, but is thickened and covered with comparatively large spinous 
scales; suborbital bone weakly spinulose; as it fails to join preopercle behind, it is less firmly fixed 
than usual; occipital region evenly rounded, -without trace of the spinous ridges so conspicuous in 
species of Ccelorhynchus. Mouth very small, the width posteriorly but 0.3 the width of head on same 
line. 
Two types of coloration appear in our specimens. Some are uniform pale brown on upper parts, 
as in the type, others have a pale spot at base of each scale forming rather definite longitudinal 
streaks above lateral line. In these specimens, the top of head and the first dorsal fin are spotted or 
mottled with dark. 
