gilbert: the lantern-fishes of japan 87 



The shape of the head resembles that of D. agassizi, having a long snout 

 protruding beyond the orbit for a distance nearly equaling the diameter of the 

 latter and a long maxillary accompanied by an oblique pre-opercular margin 

 The eye is very small and everywhere far from the profile. 



The origin of the dorsal is somewhat in advance of the middle of the length 

 (without caudal) ; posteriorly it overlaps the front of the anal. The adipose fin 

 is inserted over the last anal rays. 



Photophores. — A minute round pre-orbital on orbital rim above the level of 

 the nostril as in gemellari and agassizi. Suprapectoral very low, above and in 

 front of the pectoral, distant from it not farther than the width of the pectoral 

 base, less than one-third its distance from lateral line. Upper infrapectoral in 

 front of lower pectoral rays, not in contact with their base; lower infrapectoral 

 slightly below the line joining the upper with the first thoracic, and a little 

 nearer the upper. Fourth thoracic over middle of interspace between third and 

 fifth, barely above the level of the base of the ventral fin; second thoracic 

 midway between first and fifth, the second interspace the shortest; fifth thoracic 

 not so far out as usual, in front of middle of ventral base. Supraventral over 

 axil of ventrals, its distance from base of fin, half its distance from lateral line. 

 Third ventrals barely above base of outer ventral ray, on a level with fourth 

 thoracic and first supra-anal; fifth ventrals at sides of vent. Supra-anals in a 

 very oblique straight line, which includes also the fifth ventral, the four spots 

 equally spaced; third supra-anal buthttle in advance of the first anal, equidistant 

 between it and the lateral line. Antero-anals 5, equally spaced, in a straight 

 line, none of them elevated. Posterolateral single, directly over the interspace 

 between the two anal series, resembling an elevated antero-anal and scarcely 

 more distant from the last of that series than the antero-anals are from one 

 another. Postero-anals 6, in a straight line, the anterior very slightly elevated 

 on one side, not on the other. Anterior precaudals lying lower than the anal 

 series, the four forming a very gentle nearly horizontal curve and all equally 

 spaced; the fourth is twice as far from the lateral Une as from the lower margin 

 of the caudal fin. 



Light brownish, the margins of the scales coarsely pigmented with darker, 

 the sides of head and snout lighter. 



Only the type known; deposited in the U. S. National Museum. 



16. Diaphus nanus Gilbert. 

 Diaphus nanus Gilbert, Mem. Mus. Comp. Zool., XXVI, 1908, p. 224, PI. 1. 

 (Marquesas Islands.) 



