MYCTOPHUM LUMINOSUM. 263 
the vent and the base of the caudal, of which the two below the base of the 
caudal are separated from those in front of them and of which the sixth is 
followed by an interspace above which a lantern lies near the lateral line. 
There are indications of a very small luminous organ between the front 
edge of the eye and the upper jaw and of another between the hind 
border of the orbit and the maxillary; both are indistinct. Near the base 
of the anal several of the subcaudal scales have the appearance of covering 
mucous or luminous chambers. 
Length one and three sixteenths inches. 
Sides of head and body brilliant with an iridescent bluish or pearly 
lustre ; belly darker; back brownish; nasal sacs light ; fins light. 
Station. Latitude. Longitude. Temperature. 
3382 62° 210 N. 80° 41’ W. Surface owls 
Myctophum luminosum sp. n. 
Plate LV. fig. 2. 
Beto IG PAS da Vi, 8s 16s Ei She Iutr. 3. © at 
Form moderately stout and compressed, with regular outlines, greatest 
depth about one fifth of the entire length; caudal pedicel half as deep as 
the body; body cavity nearly half of the total distance from snout to end of 
caudal. Head medium, rounded, close upon one fourth of the entire length, 
half as wide and two thirds as deep as long. Snout short, blunt, very con- 
vex, with a prominent median internarial ridge that is not continuous back- 
ward in the middle of the interorbital space. Eye large, one fifth as long 
as the head, one and one third times as long as the snout, one half as wide 
as the interorbital space, situated immediately forward of a vertical from the 
middle of the upper jaw, covered above by a bony expansion from the skull 
passing backward as a keel at each side of the crown to end in a spine at 
the upper extremity of a ridge going down around the angle of the mouth. 
Forehead with a mucous cavity in the middle of the interorbital space and 
with another about each nasal sac, all of which are probably luminous. 
Mouth wide, two thirds or more of the length of the head. Teeth small, in 
bands on the jaws and in narrower ones on the palatines; and in a single 
short series of very small teeth on each side of the vomer. A few of the 
anterior teeth of the inner series on the palatines are larger. Nostrils 
small, anterior smaller, close together, halfway from the eye to the end of the 
