DISCUSSION OP SPECIES AND THEIR DISTRIBUTION. 267 



bifurcate or inultifiircate. Gill-membraues broadly united, free from the isthmus, no slit 

 behind fourth gill. Ventral rays i, 3. 



In addition to the type species, an Arctic form, descemling in the North Atlantic below 

 the 100 fathom line, tiiere are two or three others, found in moderately deep water off the 

 California coast. Jordan unites with this genus Artedius, but we prefer, for the present 

 at least, to consider it distinct. 



IGELUS BICORNIS, (Reinhakdt), Jordan and Gilbert. 



Coitus bicornis, Reinhardt, Vid. Selsk, Natur og Math. Afh., vm, Ixxv. 



Centridermichthys bicornis, Gunther, Cat. Fish. Brit. Hub., ii, 172. 



Icelits bicornis, .Jordan aud Gilbert, Bull, xvi, U. S. Nat. Mus., 693. 



Iceliis hamatus, Kroyer, Nat. Hist. Tidsskr., 1844, i, 253.— Gunther, Cat. Fish. Brit. Mus., ll, 172; Chal- 

 lenger Rei)ort, XXII, 63. — Collett, Norges Fisk., 35; Forh. Vid. Selsk. Christ., 1880, 14; Norsk Nordh. 

 Exped. Fisk., 34, tab. i, fig. 8; Nyt Mag. f. Naturvid, xvili, 1884, 56. — Lutken, Kara-Havets I'isk. in 

 Dijmphna-Togtot, 123; Vid. Med. Nat. For., 1876,92.— Strom, Norsk. Vid. Selsk. Skrift., 1884, 18.— Lill- 

 JEBORG, Sverig. och. Norg. Fisk., 164. 



loeliis fiirciger, AIalm, Forhaudl. Skand. Naturf., 9 Mote, 1865, 410. 



Coitus polaris, Sabine, Parry's First Voyage, 213 {fide Liitken). 



Head naked, its length 3 times in that of body. Preoperculum with 4 spines, the 

 upper 3 hooked, the uppermost bifurcate ; two bluut, occipital spines. Interocular space 

 narrow, its width 4 in eye. Dorsal separated; pectorals shorter than head. No air-blad- 

 der. Gill-membranes broadly joined, free from isthmus. 



Radial formula: D. IX, 20; A. 16; V. I, 3. 



Color, yellowish, with many brown si^ots. 



This form, first described from Spitzbergen, has since been found also in Alaska. It 

 is common in Arctic seas at small depths; of late years it has been frequently found on 

 the Norwegian coast in 50 to li.jQ fathoms. LUtken examined numerous examples from 46 

 to 106 fathoms, obtained in the Kara Sea. 



ARTEDIELLUS, Jordan. 



Arlediellus, Jordam, Cat. Fish. N. America, 1887, 110; Rep. U. S. Fish. Comm., xiii (for 1885), 1887, 898 (type, 

 Coitus nncinatns, Reinhardt). 



This genus or subgenus differs from Icelus proper, apparently its nearest ally, in having 

 the skin naked and smooth. Geiifridermivhthys, Richardson, an Asiatic genus to which this 

 aud other American species have been sometimes referred, has the skin prickly and a large 

 slit behind the fourth gdl, the gill membranes being fully united to the isthmus. 



ARTEDIELLUS UNCINATUS, (Reinhardt), Jordan. (Figure 2.55.) 



Coitus uncinatus, Reinhardt, Vid. Selsk. Natur. och Math. Afhandl., 1833, 44.— Gunther, Cat. Fish. Brit. 



Mus., II, 172; Challenger Report, xxil, 1887, 62. 

 Centridermichthijs uncinutns, Coi.lett, Norsk. Nordh. Exped. Fisk., 23, tab. i, tig. 7; Forh. Vid. Selsk. Christ., 



1880, 14; Nyt Mag. f. Naturvid., xviii, 1884, 54.— Lutken, Kara-Havets Fisk. lii Dijuiphua-Togtet, 124. — 



LiLi.JEBORG, Sverig. t>ch Norg. Fisk., 161. 

 Icelus uncinatus, Kroyer, Nat. Tid., 184-4, 253.— Jordan and Gilbert, Bull, xvi, U. S. Nat. Mus., 693. 

 Coitus bicornis, Reinhardt, loc. cit., viii, 75. 

 Artediellus uncinatus, Johdan, loc. cit. 



Body fusiform, its height contained 4i times in its total length. Head broad, its length 

 one-third that of the body; lower jaw included. Palatine teeth well developed. Maxillary 

 extending to opposite middle of pupil. Eyes very large, separated by a narrow ridge; 

 occiput with two blunt ridges, in front of which the vertex is concave; upper preopercular 

 spine large, strongly hooked upward, more than half length of eye; downward-directed spine 

 onpreopercle long and .sharp; .skin perfectly smooth. Pectorals reaching front of anal; 

 spinous dorsal rather high; vent midway between snout and middle of caudal. (Jordan 

 and Gilbert.) 



Radial formula: D. viir, 13; A. 11. 



"An Arctic littoral species," writes Giiuther, "more or less common in the sea between 

 Greenland, Spitzbergen, Nova Zembla, and Norway, extending in the western part of its 



