30 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



KEY TO THE SPECIES OF ALEPOCEPHALUS. 



I. Oi)cr(ul:ir flaps voluminous; head large. 



A. Head one-third of total or nearly so. 



1. Scale.'^ large (SO-.T), in lat. line). Snout, 10 in hody length. Eye, 3i in head A. l!o.sTRATr,s 



2. Scales moderate {G7 in lat. line). Snout, 9 in body. Eye, 4 in head A. puoducti'S 



3. Scales moderate (70 in lat. line). Snout 10* in hody. Eye 3| in head A. Blanfordii 



4. Scales small (al)out 90 in lat. line). Snout, 12 in hody. Eye, 3i in head A. Aga.ssizii 



B. Headless than one-third of total. 



1. Scales very small (about 140 in lat. line). Snout, 10 in total. Eye 6 in head A. NlGF.lt 



1. Oiicrcular (lai)S moderate; head moderate. 



1. Scales large (65 in lat. line). Snont 18 in hody. Eye 4J in head A. Baihdii 



2. Scales large (62 in lat. line). Snout lu in body. Eye 6 in head A. bicolor 



3. Scales large (.50 in lat. line). Snout 18 in body. Eye U in head A. edentui.L's 



There are two distiuct groups in AJepocephahts, probably of subgeneric value. The 

 first group iucludes the type, A. rostratm, Eisso. It is characterized by a somewhat short, 

 compressed body, large head, with extended membranaceous Haps, and by short dorsal aud 

 anal fius, similar in size and shape and nearly oppo.sitc each other. 



A. rostratus has the largest scales, 50 to 55 in the lateral line (Vaillant claims to have 

 counted 71 on a large individual), and has a comparatively large eye and suout. 



.1. Af/Ksxizii has somewhat smaller scales (about 90 in the lateral line), a comparatively 

 larger head (3 in total), and the eyes slightly larger (3.J in head, lOJ in body). 



A. productus has a smaller eye than A. AgassizH, and a longer suout, it being about 

 one third of the length of the head. In A. rostratus, however, the snout length is one- 

 tenth of the total; in A. productus one-twelfth. 



A. Blanfordii, Alcock (Ann. and Mag. Nat. Hist, 1892, ii, 357), from the Indian Ocean, 

 has an immense eye. 



A. niger of Giinther is a somewhat slenderer form, with very small scales. 



All of these forms are dull in color and have the ventral tins weak and inconspicuous. 



A. Bairdii represents another type, having a stout body, about as high in iiroportion to 

 its length as in A. A(/asxizii, etc., but with a smaller head and less voluminous opercular flaps 

 The eye is comparatively much smaller (18 in total length), and is nearer the upper i)roflle 

 of the head. The vertical fins are stronger and more muscular, and are heavily scaled at 

 their bases. Lateral line nearly straight. Maxillaries slender, not expanded posteriorly. 



A. bicolor, Alcock (Ann. and Mag., 1891, ii, 133), is from the Indian Ocean, 240-76 

 fathoms. 



A. cdentulm, Alcock, I. c. is from the Indian Ocean, 475 fiithoms. 



ALEPOCEPHALUS ROSTRATUS, Risso. (Figure 41.) 



Alepoccphalus rostratus, Rl.s.so, Mem. Acead. Torin., xxv, 1820, 291, pi. x, fig. 4; Hist. Nat. de I'Europe M<Sri- 

 dionale, 449, iig. 27. — Cuvier and Valenciennes, Hist. Nat. Poiss., xix, 169, pi. 532.— Johnson, Ann. 

 and Mag. Nat. Hist., x, 1862, 285.— GCnther, Cat. Fish. Brit. Mus., vii, 477.— Moreau, Hist. Nat. Poiss. 

 Fran<-e, III, 463.— Gegenuadr, Morphol. Jahrhuch, iv, Suppl., 1, pi. 1, 2 (.skull). — Giglioli, Elenco, 

 1883, 106.— Vaillant, Exp. Sci. Trav. et Talisman, Poissons, 148, pi. xi, fig. 1; pi. xn, fig. 5. 



The height of the body is a little more than one-fifth of the total length (without caudal) ; 

 the length of the head is a little less than one-third. Diameter of the eye contained thrice 

 and one-fourth in the length of the head, and longer than the snout. Scales much longer 

 than wide, with the anterior (radical) margin truncated. Origin of the dorsal fin opposite 

 to the vent. I'ectoral fin longer than orbit. Distance of ventral fin from the head three- 

 fifths the length of the latter. Uniform deep black. {Giinther.) 



Kadial formula: B. 6; D, 16, 17; A. 18, 19; P. 13; V. 8; L. lat. 55; Ccec. pyl. 12. 



This species occurs in the deeper waters of the Mediterranean, and was described by 

 Risso in 1820. Until 1874, when the Challenger began her work, this was the only repre- 

 sentative of the family known to ichthyology. 



The French expedition obtained twenty-four specimens from ofl' the coasts ()f Soudan 

 and Morocco, from about 830 to 2,190 meters, from the Banc d'Arguin; from the Canaries, 

 975 meters; the Azores, 2,235 meters, and the Cape Verde Islands, 3,655 meters. Giinther 

 is disposed to believe that Esiinciijus Costal is the young of this species. 



