78 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



BENTHOSEMA ARCTICUM, (LOtken), Goode and Bean. 



Scopelus articus, LOtken, Spolia Atlantica, ii, 1892, 249, Fig. 6. 



A species apparently more closely related to B. MiiUfri than to any other form, but 

 having no posterolateral photophore and no break in the series of snperanals, the uumber 

 of which is fitteen or sixteen. It has two mediolaterals iu subhorizoutal line, continuous 

 with the two anterolaterals. It is a much shorter-bodied form than 7>. (jhicidlis, and has a 

 much shorter and higher first dorsal. Liitken's figure shows only one opercular photophore, 

 instead of two, which are customary. Kadial formula: D. 9; A. 17; P. 14; V. 8. 



Liitken's types were four specimens obtained from Greenland and one from Davis's 

 Strait, Two of them have a large supracaudal luminous plate, and three others small 

 intracaudal luminous plates. 



BENTHOSEMA COLLETTI, (Lutken), Gooue and Hkan. 



ffcnpelus Colletti, L'Jtkbn, Spolia Atlantica, ii, 1892, 249, Fig. 7. 



A species having the photophores arranged somewhat as in B. arcticum, but with the 

 two mediolaterals in a subverticalliue continuous with the last of the ventral photophores, 

 instead of approximately with the anterolaterals. There is no posterolateral photophore. 

 The superanaLs are in a continuous row, 10-17 in number. Head somewhat blunt; pectoral 

 short, as in B. arcticum, reaching about to the vertical from the origin of the first dorsal. 



Radial formula: D.15; A. 21; L. lat. 38. 



This species is described from a single specimen in the Museum at Christiania, obtained 

 from the Pacific, 600 miles west of Cape Horn. 



LAMPANYCTUS, Bonaparte. 



Lampanyctus, Bonaparte, Faim. Ital., fasc. xxvii.— Gunther, Cat. Fish. Brit. Mus., v, 414 (as subgenr.s). 



Myctophid flslies, with long head, conical snout, limb of preoperculum oblique; dorsal 

 about equal to or shorter than anal, and not overlapping. Lateral line not much enlarged. 

 Scales cycloid, smooth. No orbital spines. Scales smooth, those in the lateral line scarcely 

 larger than the others. Maxillary scarcely dilated behind. Precaudal photophores 4 or 2 + 1. 



KEY TO THE SPECIES OP LAMPANYCTUS. 



I. Pectorals loug; preoaudals in two groups (2+1, 3+1, or 2+2), the last on or near end of lateral line. 



A. Mediolaterals 2; posterolaterals 2, nearly under soft dorsal. 



1. D. 12-13; A. 14-15; L. lat. 38-9; super.anals 6-8+8-12 L. crocodilus. 



2. D. 13; A. 15; L. lat. 32-3; superauals 7+6 l. alatus. 



B. Mediolaterals 3; posterolaterals 2, iu advance of soft dorsal; preoaudals 3+1. 



1. D. 12-13; A. 14-13; L. lat. 36; superanals 5+5. 



a. Anterolaterals 2 ; pectoral extending beyond mediolaterals and to middle of anal 



L. GiJNTUERI. 



2. D. 12-13; A. 13; L. lat. (?); superanals 7+5. 



a. Anterolaterals none; pectoral not reaching mediolaterals or origin of anal L. warmingii. 



II. Pectorals long; precaudals 4, in continuous, nearly horizontal, row, not approaching end of lateral line. 

 A. Mediolaterals 2; posterolaterals 2, nearly under soft dorsal. 



1. D. 12; A. 16; L. lat. 38; superanals 7+8. 



a. Anterolaterals 3, horizontal, nearly in line with lowest mediolateral L. gemmifer. 



III. Pectorals short; precaudals 4, in low, nearly horizimtal line, not ajiproachiug end of lateral line. 

 A. Mediolaterals 3. 



1. Posterolaterals 2, in advance of soft dorsal. 



a. D. 14; A. 12; L. lat. 35; superanals 4-5+5-6 L. gemellarii. 



b. D. 12-13; A. 19; L. lat. 33; snperanals 6+5 i.. CffiRULEUS. 



2. Posterolateral 1, placed under soft dorsal. 



a. D. 12' A. 12-13; L. lat. 36: superauals 5-7+5 l. lacerta. 



