PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 275 



groove. A groove between the frontal bones. Orbital margins sep- 

 arated by a groove from the preopercle. Margin of preopercle very 

 ubliqne. All the membrane bones extremely thin, membranaceons. 

 Eye large, 3^ in head. Gill-rakers long and slender. Head 3f in length 

 to base of candal ; depth 4J. 



Head and body completely covered with thin membranaceons scales, 

 those on the middle of the sides not elevated and not noticeably larger 

 than the others. Free edges of all the scales crenulate, some of them, 

 especially on the back, with the crenations acute, but without spines, 

 the scales not being really ctenoid or spinous. About 45 scales in a 

 longitudinal series. 



A i)hos]»horescent spot on each mandible near the symphysis, 33 pairs 

 of spots along the belly, 6 in front of ventrals, 6 between ventrals and 

 origin of anal, and 21 between front of anal and base of caudal. 



Caudal peduncle above and below with two or three backward-di- 

 rected spines, which are apparently the exserted tips of vertebral i>yo- 

 cesses. 



Fin rays (not quite certain, the tips being frayed out) : Dorsal about 

 12, anal about IG, the fins rather low. 



Origin of dorsal nearer the snout than the base of caudal, much behind 

 the base of the ventrals. Ventrals short, not reaching halfway to vent- 

 Pectorals reaching base of ventrals. 



Color very dark steel-blue above, silvery on sides and below, with 

 dark metallic luster. The usual phosphorescent spots present, as above 

 described. No evident cream-colored blotch on the back of tail. 



Myctophum crenulare is known to us at present from a single speci- 

 men, about 1^ inches long, taken from the stomach of an Albicore ( Or- 

 cynvs alaJonga) in Santa Barbara Channel, July 11, 1880. It had evi- 

 dently just been swallowed, and is in fairly good condition. 



It belongs to that division of the genus " Scopclus " called by Dr. 

 Giinther " Myctophum " (Cat Fishes Brit. Mus., v, 405). As the latter 

 name has priority over tScopelus^ it must be retained as a generic name 

 for some or all of these fishes. 



Tabic of measurements. 



Extreme length 2.20 inches 



Length to base of caudal 1.80 inches = 100 



Body: 



Greatest depth 23 



Least depth of tail 4 



Length of candal pednncle 22 



Head : 



Greatest length 27 



Width of interorbital 



Length of maxillary 19 



Tjength of snout 3 



Diameter of eye 8 



Dorsal, distance from snont 51 



Anal, distance from snont , r)4 



Pectoral, length 9^ 



