THE LANTERN FISHES. 221 



Dasyscopelus asper (Richardson). 

 Myctophum asperum Richardson, Ichth. Erebus & Terror, 1845, p. 41, pi. 27, figs. 13-15. 



Four specimens not exceeding 20 mm. long, taken at the surface Sept. 8, 

 1899, in Lat. N. 3° 28', Long. W. 136° 54', about 700 miles north of the 

 Marquesas Islands. 



Most nearly related to Myctophum pristilepis, Gilbert & Cramer, from the 

 Hawaiian Islands, differing in the higher, more compressed head, the 

 blunter, somewhat projecting snout, the much smaller eye, which is far 

 below the upper profile, the more angulated supra-anals, and the slightly 

 more distant precaudals. The number of anal photophores is larger. 



Measurements in hundredths of length to base of caudal : length of head 

 32 ; eye 9 ; axial length of snout 4.5 ; greatest depth of body 26 ; least 

 depth of caudal peduncle 9 ; distance from snout to front of dorsal 46 ; to 

 base of ventrals 47 ; to front of anal 62 ; to adipose dorsal 82. 



Dorsal 13, anal 17, pectoral 15, lateral line 37. 



Head and body comparatively deep and compressed, eye small, well 

 below the upper profile, snout high and compressed, slightly protruding 

 beyond premaxillaries. Maxillary little widened posteriorly, extending 

 beyond eye a distance less than half orbital diameter. Teeth all straight, 

 in very narrow bands, consisting of a series of somewhat longer teeth with 

 smaller ones interspersed. Cheeks not oblique, the posterior border of 

 preopercle vertically rounded. 



Pectorals long, extending to or slightly beyond middle of ventrals ; 

 ventrals reaching vent, inserted a trifle behind origin of dorsal ; first anal 

 ray under the last of the dorsal, its last rays under the adipose fin. 



Scales mostly fallen, those present showing a few coarse serroe. Two 

 minute antorbital photophores, one above the other below level of nostrils, 

 the two connected by a narrow black bar. Supra-pectoral slightly nearer 

 pectoral fin than lateral line ; upper infra-pectoral opposite base of lower 

 pectoral ray, the lower infra-pectoral nearer the upper than the first pair 

 of ventrals. First pair of ventral photophores nearest the median line, the 

 second, third, and fourth pairs nearly equidistant from it, the fifth pair 



