666 
BULLETIN OE THE UNITED STATES FISH COMMISSION. 
acteristic of H. antrxus; a conspicuous black spot at base of each anal ray; dorsal rays not marked; 
posterior edge of occipital canal jet-black (as in H. antrxus)-, a transverse black line on anterior edge of 
snout; lower side of head, opercle, breast, and belly black, this color extending a little beyond origin 
of anal fin. As in II. antrxus, the gular membrane has a black median streak, from which diverge 
forward and outward a number of fine parallel black lines. A silvery streak along each side of isthmus 
extending backward and surrounding outer portion of ventral base, crossed with very fine parallel hair 
lines of black, which can be made out only by the aid of a lens; these lines are as numerous and as 
fine as the scale strife; lips and dentary portions of jaws black; roof of mouth shining plumbeous; 
branchial region largely dusky; a blackish patch in front of tongue; lining of gill-cavity largely dusky. 
Specimens were taken as the following stations: Nos. 3920, off the south coast of Oahu, 265 to 280 
fathoms; 3986, off Kauai, 55 to 362 fathoms; 4122, off the southwest coast of Oahu, 192 to 352 fathoms. 
Hymenoeephalus aterrimus, new species. Plate 93. 
Type, 127 mm. long, from station 3989, vicinity of Kauai Island, depth 385 to 500 fathoms; type, 
No. 51649, U. S. Nat. Mus. 
This species is jet-black, and occurs at a greater depth than II. antrxus or H. striatulus. Its range 
is apparently between 400 and 500 fathoms, where it is found in company with Macrourus gibber 
and Trachonurus sentipellis. It is closely related to the other Hawaiian species of the genus, and to 
H. italicus. In addition to the papery cranial crests and the wide mucous canals bridged over with 
delicate membrane, the. wide terminal mouth, the weak dentition and the smooth dorsal spine, the 
species has thin caducous scales, the peculiar striation on side of throat and region above base of 
pectoral fin, and the 2 minute lens-like bodies in the median line of the ventral surface. 
The depth of the body varies widely with the distention of the abdomen, and also with the curvature 
of the back, the base of the dorsal fin sometimes forming a greater prominence than in the type. In 
the latter, the depth at origin of dorsal fin is contained 1.5 times in the length of the head. D. ii, 9; 
V. 13 (usually 14); P. 13 (sometimes 14); 3 rows of scales between position of lateral line and middle 
of base of first dorsal. 
Head very large, compressed, with a very heavy bluntly-rounded snout, which scarcely protrudes 
beyond premaxillaries; mouth terminal, with the premaxillaries anteriorly wholly below orbit; cleft 
oblique; maxillary reaching slightly beyond vertical from posterior margin of orbit, its length 1.85 in 
head ; teeth very short and slender, but somewhat longer than those in H. antrxus and II. striatulus, 
arranged in narrow bands in both jaws, the inner series evidently longer than the outer but still very 
small; all the teeth are depressible; with a lens they are seen to be arrow-shaped at tip; barbel wanting; 
eye small, shorter than snout, and but half width of interorbital space; preopercle very widely expanded, 
its angle broadly rounded, its upper limb oblique and convexlv curved ; around preopercular angle 
the margin is rather coarsely crenate; gill-membranes moderately joined anteriorly, wholly free from 
isthmus; gill-slits wide, the membranous attachment to the first arch encroaching less on anterior cleft 
than in species of Macrourus; a narrow slit behind fourth arch; gill-rakers short, sessile, spinous; in 
uninjured specimens the tail is extremely slender. 
As in related species, the first dorsal spine is minute, not evident to the eye; the second spine 
very slender and wholly smooth, tapering to a very fine point, but not filamentous; the succeeding ray 
unbranched, but articulated, the 4 following rays forked for a short distance near their tips; other rays 
simple, unbranched; rays of second dorsal very small, but origin of fin can be made out without diffi- 
culty; interspace between dorsals equal to 2.4 times base of anterior dorsal; second dorsal spine 0.6 length 
of head; origin of anal fin vertically behind first dorsal for a distance equaling diameter of pupil; anal 
rays high, 0.3 length of head; vent immediately in front of first anal ray; pectoral narrow and long, one 
of the upper rays elongate, reaching vertical of ninth anal ray, 0.6 length of head; outer ventral ray a 
long slender filament, reaching the same vertical as pectoral filament, 0.7 length of head; ventrals 
inserted in advance of pectoral base by a distance equaling diameter of pupil. 
Scales large, very thin and caducous, round in outline, with parallel concentric lines whose centers 
coincide with those of the scales; no spines on any of the -few scales examined, these including all the 
scales of the breast, a few above and behind bases of ventrals, those between pectorals and ventrals, 
those behind and above bases of pectorals, and one above bases of anterior anal rays; the scales evi- 
dently covered the entire body in fife, but may have been absent on head. 
