282 CONTRIBUTIONS TO NORTH AMERICAN ICIITIIVOLOGY IV. 
loric (Mi'ca few. Dorsal liii near the middle of the body; ventrals 
usually below it, with 8 rays; pectorals well developed; adipose liii 
small; anal usually long'. Small fishes of the open seas iii most re- 
gions; spi'cies numerous. Several uiidescribed species have been lately 
taken olf our Atlantic coast by the U. S. Fish Commission. night; 
light; hence amended by Cocco to i/ctophiis.) 
!<><>. .TI. «‘D‘<*1!*b«!1sib’C .Ionian & GilBcrt. 
llody much compressed, deepest in front of the base of the pectorals, 
bluntly convex anteriorly, tapering behind. Ventral region much more 
arclual than dorsal. Caudal peduncle long and veiy slender. Head 
short and high, abruptly rounded in profile, the snout very blunt, 
daws eipial, the snout not iirojecting beyond the mouth. Maxillary 
very slender, scarcely widened to its tip, and not dilated, its extremity 
reaching beyond the eye to the margin of the preopercle. Premaxilla- 
ries anteriorly on a level of the pupil. Teeth very small, iiresent on 
all the dentigerous bones, llami of the mandible nearly parallel, com- 
ing together in a sharp keel below. Orbital margin above and in front 
with a thin membranaceons rim, that in front distiiutt and formed by 
the upturned edge of the preorbital. Xo orbital spine. Xasal bones 
membranaceous, their edges upturned, forming a horizontal groove. 
A groove between the frontal bones. Orbital margins separated l)y 
a groove from the preopercle. Margin of preopercle very obliipie. 
All the membrane bones extremely thin, paper^N Eye large, in 
head. Gill-rakers long and slender. Ilead of in length to base of 
caudal ; depth 4.C Uead and body completely covered with thin mem- 
branaceous scales, those on the middle of the sides not elevated and 
not noticeably larger than the others. Free edges of all the scales 
crenulate, some of them, especially on the back, with the crenations 
acute, but without spines, the scales being truly cycloid. About 45 
scales in a longitudinal series. A phosphorescent spot on each man- 
dible near the symiihysis, 33 jiairs of spots along the belly, G in front 
of ventrals, G between ventrals and origin of anal, and 21 between 
front of anal and base of caudal. Caudal peduncle above and below 
with two or tliree backward-directed spines, which are apiiarently the 
exserted tiiis of vertebral processes. I). 12; A. IG; the fins rather 
low. Grigin of dorsal nearer the snout than the base of caudal, much 
behind the base of the ventrals. Ventrals short, not reaching half way 
to vent. Pectorals reaching base of ventrals. Color very dark steel- 
blue above, .silvery on sides and below, with dark metallic lustre; the 
