78 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



BENTHOSEMA ARCTICUM, (Lutken), Goode aud Bean. 



Scopelus articus, Lutken, Spolia Atlantica, n, 1892, 249, Fig. 6. 



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

 having no posterolateral photophore and uo break in the series of superanals, the number 

 of which is fifteen or sixteen. It has two mediolaterals in subhorizontal line, continuous 

 with the two anterolaterals. It is a much shorter-bodied form than B. glacialis, and has a 

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

 instead of two, which are customary. Eadial 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 

 infracaudal luminous plates. 



BENTHOSEMA COLLETTI, (Lutken), Goode and Bean. 



Scopelus Colletti, Lutken, Spolia Atlantica, n, 1892, 249, Fig. 7. 



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

 two mediolaterals in a subvertical hue 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. 



Eadial 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, GUO miles west of Cape Horn. 



LAMPANYCTUS, Bonaparte. 



Lampanyctus, Bonaparte, Faun. Ital., fasc. xxvii.— Gunther, Cat. Fish. Brit. Mus., V, 414 (as subgenus). 



Myctophid fishes, with long head, conical snout, limb of preopereulum 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 OF LAMPANYCTUS. 



I. Pectorals long; preeaudals in two groups (2+1, 3+1, or 2+2), the last on or near end of lateral Hue. 



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



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



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



B. Mediolaterals 3; posterolaterals 2, in advance of soft dorsal; preeaudals 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. GUNTHERI. 



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; preeaudals 4, iu 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; preeaudals 4, in low, nearly horizontal line, not approaching 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; superanals 6+5 l. cceruleus. 



2. Posterolateral 1, placed under soft dorsal. 



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



