iSIYCTOPIIUM LUMINOSUJI. 2G3 



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 tin-ee 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 6° 21' N. 80° 41' W. Surface 75° F. 



Myctoplium luminosum sp. n. 



Plate L r. fig. 2. 



Br. r. 8 ; D. 16 ; A. 14 ; V. 8 ; P. 16 ; LI. 35 ; Ltr. 3 7. 



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, clo.se npon 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 aromid the angle of the mouth. 

 Forehead with a mucous cavity in the middle of the interorbital s[)ace 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 vouier. 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 



