678 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Snout high and compressed, protruding beyond mouth for an axial distance nearly equaling half 
orbital diameter; anterior profile of snout very oblique; distance from its tip to premaxillaries contained 
4.7 in length of head; length of snout 0.8 longest orbital diameter, and contained 3.5 times in length of 
head; interorbital space convex, with somewhat depressed central area, its width 0.3 length of head; 
longest orbital diameter very slightly more than 0.3 length of head; nasal fossa scaled in its posterior 
half, the longitudinal diameter of naked portion half that of pupil; length of the posterior nostril 0.4 
pupil ; top and sides of head without conspicuous ridges; greatest width of mouth, measured externally, 
contained 1.8 times in its greatest length; maxillary reaching a vertical which intersects orbit halfway 
between pupil and hinder margin of orbit, it's length contained 2 or 2.1 times in length of head; pre- 
maxillary teeth in a double series, the outer of moderate canines, which decrease in size laterally, the 
inner of much smaller curved teeth directed backward; mandibular teeth uniserial, except at sym- 
physis, where 2 teeth on either side stand behind 2 of the outer row; anterior teeth about equal to 
those to which they.are opposed in upper jaw; lateral teeth increasing in size backward, and becoming 
the largest in the mouth; barbel half or slightly more than half orbital diameter; preopercular angle 
broadly produced backward, the posterior margin very oblique and incurved; above opercle, a wide 
band of scales covers scapular region, separated from neighboring scaly areas above and below by 
narrow naked lines; gill-membranes rather narrowly joined across isthmus, forming a fold which is 
entirely free; anterior gill-slit less constricted than usual, its width 3 times that of slit behind fourth 
gill; gill-rakers 7 in number, tubercular, but unusually prominent, slightly movable, and bearing long 
spinous teeth; no exposed spines in connection with opercles or shoulder-girdle. 
Second dorsal spine very slender and weak, not extending beyond the tip of the following ray and 
not filamentous, its length 1.6 times in head, very slightly exceeding length of snout and eye; second 
dorsal very low, but perfectly distinct throughout its course, its first ray about over thirtieth anal ray; 
interspace between dorsals unusually long, equaling about 2.5 times the base of anterior fin; length of 
interspace is not described or figured in M. Ixvis, in which the second dorsal is said to be so low and 
indistinct as to render uncertain the point of origin; anal fin low, its origin vertically under third ray 
of first dorsal; distance from anal opening to point where edge of branchiostegal membrane crosses 
isthmus half length of head. In M. Ixvis Gunther finds the “distance between the vent and isthmus 
two-thirds of the length of the head.” Pectorals shorter than in M. Ixvis, half length of head, and con- 
taining constantly 19 or 20 rays, instead of 17 or 18, as in that species; outer ventral ray produced, 
reaching base of tenth or twelfth anal ray. 
In M. hawaviensis, as in M. Ixvis, there is a deep, scaleless, transversely elliptical pit between bases 
of ventral fins, but in the Hawaiian species the pit is smaller. The anus is equidistant from the base of 
ventrals and the first anal ray, or slightly nearer anal, and lies .at the posterior end of a longitudinally 
oblong or wedge-shaped naked area, which is separated from the anterior pit by a narrow band of 
scales. There is no trace of a constriction dividing anal area into a posterior linear portion containing 
anus and an anterior oblong portion, as is figured by Gunther in M. Ixvis. The descriptions by Gunther 
and by Liitken do not, however, agree with the interpretation of the artist. Lutken describes the 
position of the anal opening in M. Ixvis as beneath the fourth ray of the first dorsal, and behind base 
of pectorals. In hawaiiensis a vertical from the anus traverses the pectoral base and the base of second 
dorsal spine. 
The scales are very small, high and narrow, caducous, those on posterior part of body lost in all 
specimens which we have obtained; under anterior dorsal, each scale is densely covered with short 
spines which show no evident arrangement; scales on nape and breast similar; on top of head the 
spines are similar, but frequently arranged in parallel or diverging lines; no arrangement is apparent 
on sides of head; head very completely scaled; lips and half the nasal fossae naked; gular membrane 
with spinous plates on median line only, and those on gill-membranes confined to single series accom- 
panying rays; with these exceptions all exposed surfaces of head are densely covered; the lateral 
line describes a long convex curve anteriorly, and reaches middle of sides more than a head’s length 
behind its origin. 
Color olive-brown above, bluish silvery on sides of head and trunk; gill-membranes and abdomen 
black; mouth cavity white, gill-chamber black, except the part overlying the epihyal and ceratohyal; 
abdominal cavity lined with black; first dorsal, ventrals, pectorals, and anterior portions of dorsal 
and anal fins black. 
