234 DEEP SEA FISHES. 
Argyropelecus lychnus sp. n. 
Plate J, fig. 1, 1 6b. 
Brar.9 3. D. Vile 4-395 Arie Oi Oe eee. 
Very narrow and very deep in the body, half as deep and narrower in 
the caudal section. Body cavity more than half of the total length, as also 
is the greatest depth. In young stages the depth is much less as compared 
with the length. Length of the head about half of the depth of the body or 
one third of the length from the snout to the caudal notch; forehead very 
narrow, with two longitudinal keels separated by a narrow groove, narrower 
in the interorbital space. Eye large, less than half of the head. Snout 
short, two thirds as long as the eye, blunt; chin nearly vertical, with a 
small symphyseal protuberance. Mouth wide; maxillary twice as long as 
the eye, forming rather more than half of the upper border of the mouth. 
Teeth small, acicular, separated, in single series; there are eleven or twelve 
on the intermaxillary, of which the third or the fourth is the largest; there 
are sixteen, more or less, on the maxillary, half of them hooking backward 
and the posterior six or eight hooking forward; the dentary teeth are 
longer and erect, with the exception of a few of the anterior which are 
hooked, the fifth or the sixth being decidedly so; the few on the anterior 
portions of the palatines are minute. Gill rakers long, half the length of the 
eye, slender, eight (seven to nine) on the upper portion of the first arch 
and eight to ten, with two or more rudiments, on the lower. A small spine 
above each shoulder on the nape; a spine below the preopercle; another 
less prominent below the angular. Ventral spine in two sections, of which 
one turns forward, the other backward. Dorsal blade containing seven 
spines, upper edge not denticulate. Anal fin in two divisions, indicated by 
a larger interspace between the rays. Pylorie cxca six to seven or to five. 
The blade in front of the dorsal fin, and the abdominal keel are not serrate. 
The lanterns, luminous organs, are distributed thus: one on the fore- 
head; one in front of and one behind the eye; two backward of the end of 
the maxillary ; two above and backward from the base of the pectoral, and 
six behind these, directly backward of the base of the fin ; and six in the 
branchiostegal, six in the pectoral, twelve in the abdominal, four in the 
ventral, six in the anal, and four in the subcaudal section of the lower or 
ventral series. In these lanterns the disk is in the upper part while the 
elongate lower portion is silvered as if for purpose of reflection. 
