596 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Myctophum fibulatum Gilbert & Cramer. 
Two specimens, dredged at depths of 220 to 284 fathoms, do not differ from the type in number 
and distribution of the photophores. The species is peculiar in having but 3 equally spaced pairs 
of ventral photophores along median line, the second pair being displaced laterally, almost vertically 
above the first pair. The anterior pair of the supra-anals lies over the interspace between the third 
and fourth ventrals. A small black-ringed photophore on the anterior orbital rim escaped notice in 
the type. One small specimen was taken in the surface tow-net, at station 3889, north of Molokai ; 
others were obtained at stations 3899, Pailolo Channel, 283 to 284 fathoms, and 4082, off the north 
coast of Maui, 220 to 238 fathoms. 
Myctophum fibulatum Gilbert & Cramer, Proc. U. S. Nat. Mus., xix, 1897, 411, pi. 38, fig. 2 (not fig. 3, as erroneously indi- 
cated on plate 38 and in the description). 
Myctophum marg-aritatum, new species. Plate 68, Fig. 2. 
Type 80 mm. long, from the surface at station 3930, off the south coast of Molokai; type, No. 
51536, U. S. Nat. Mus. 
Closely related to M. affine Lfitken and M. opalinum Goode & Bean, from the Atlantic. These 
two species are insufficiently described, and may even prove to be identical with each other and with 
the species here described. Certain differences are, however, indicated in the descriptions as they 
stand. 
Greatest depth of body 24 hundredths of total length without caudal; least depth of caudal 
peduncle 8; length of head 27; diameter of orbit 9; interorbital width 10; length of snout 4; length of 
maxillary 17; distance from tip of snout to front of dorsal 44, from front of dorsal to adipose dorsal 37, 
from front of adipose dorsal to rudimentary caudal rays 21, from tip of snout to ventrals 41, from tip 
of snout to origin of anal 57; base of anal 27; length of pectoral 15; length of ventral 12. D. 13; A. 20; 
P. 15; V. 9, the outermost ray minute; scales in the lateral line 40, the 41st on the base of the caudal 
fin and without tube; 9 scales in a cross-series excluding median rows on back and belly. 
Body rather slender, heavy forward, snout very short and bluntly rounded, the profile descending 
in a strong, nearly uniform curve from occiput to front of nostrils; eyes very large, one- third length of 
head, slightly less than frontal width above their middle; snout and frontal region with low concealed 
median crests; mouth oblique, maxillary gradually w. !ening posteriorly, extending well behind the 
orbit, its length slightly less than two-thirds that of head; teeth minute, in narrow bands in each jaw, 
those on vomer in 2 small, widely separated clusters, those on palatines larger than the others, in single 
series; in addition to these, all the roof of the mouth, except its middle line, is covered with minute 
asperities; preopercle nearly vertical, its margin entire; opercle entire and unstriated, except for a 
short space below the upper posterior angle,. where the margin is weakly ribbed and toothed; gill- 
rakers long and slender, 5+16 on outer arch, the longest slightly more than half the diameter of orbit. 
First dorsal ray over the eleventh scale of lateral line; root of ventrals opposite the ninth or tenth; 
first anal ray under the eighteenth, last under the thirty-first; origin of adipose dorsal over the twenty- 
ninth; pectorals not reaching middle of ventrals; ventrals not reaching vent. 
Scales all thin, not spinous, the margins entire or only gently notched or sinuate, those of the 
lateral line not enlarged. 
Photophores arranged as in M. affine Gunther and M. opalinum. Goode & Bean; preoculars 1, 
minute, similar to those on body, on the lower anterior orbital rim; mandibulars 3; operculars 2, 
the one behind the tip of maxillary concealed beneath the margin of the preopercle; pectorals 3, 
forming a right angled triangle, the middle spot on lower edge of pectoral base, the upper encroaching 
on third scale of lateral line, the lower on line between pectoral base and the first thoracic spot; 
thoracics 5, the third and fourth less widely separated than the others, the 5 pairs arranged in 2 nearly 
straight gently diverging lines; supra- ventrals 1, nearly midway between the axil of the ventrals and 
the lateral line; ventrals 4, equally spaced; supra-anals 3, in an oblique line directed toward interspace 
between third and fourth ventrals; anals 13 to 17 (usually 14 or 15), in 2 well-separated groups, 
8-10+5-7, the usual formula being 9+6, 9+5, or 10+5, the series throughout parallel with the lower 
outline; posterolateral 1, over the last antero-anal; caudals 2, closely approximated, the posterior little 
higher than the anterior; the third supra-anals and the posterolaterals encroach upon the series of 
scales which bear the lateral line, the former below the eighteenth, the latter below the twenty-eighth 
