DISCUSSION or SPECIES AND THEIR DISTIJII'.FTiON. 



2G7 



bifurcate or multifurcate. Grill-membranes broadly united, free from the isthmus, no slit 

 behind fourth gill. Ventral rays i, '■'>. 



In addition to the type sj Les, an Arctic form, descending in the North. Atlantic below 



the Inn fathom line, there arc 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. 



ICELUS BICORNIS, (Reixhakivt), Jordan and Gilbert. 



Cottua bicornis, Reinhabdt, Vid. Selsk, Natur og Math. Al'h.. via, lxxv. 



Centridermichthya bicornis, GOnther, Cat. Pish. Brit. Mus., n. 172. 



I, tins bicornis, JORDAN and Gilbert, Bull, xvi, II. S. Xat. Mus., 693. 



Icelus hamulus. Ivroyer, Nat. Hist. Tidsskr., 1844, i, 253. — GDnther, Cat. Fish. Brit. Mus., n, 172; Chal- 

 lenger Report, xxn, 03. — Collett, Norges Fisk.. 35; Forh. Vid. Selsk. Christ., 1880, 14; Norsk Nordh. 

 Esped. Fisk., 34, tal>. i. fig. 8; \yt Mag. f. Naturvid, xvm, 1884, 56. — Li'tken, Kara-Havets lisk. in 

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

 jeborg, Sverig. och. Norg. lisk., 104. 



Icelus furoiger, Malm, Forhandl. Skand. Naturf., 9 Mote, 1805, 410. 



Coitus poluris, SABINE, Parry's First Voyage, 213 {fidr Liitken). 



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

 upper 3 hooked, the uppermost bifurcate; two blunt, 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; -V. 10; V. i, 3. 



Color, yellowish, with many brown spots. 



This form, first described from Spitzbergeu, 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 L'.IO fathoms. Liitken examined numerous examples from 46 

 to 100 fathoms, obtained in the Kara Sea. 



ARTEDIELLUS, Jordan. 



Arlediellus, Jordan*, Cat. Fish. N. America, 1887, 110; Rep. U. S. Fish. Couim., xm (for 1885), 1887, 898 (type, 



Cottus uncinatus, Reinhardt i. 



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

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

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

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



ARTEDIELLUS UNGTNATUS, (Reinhardt), Jordan. (Figure 255. 1 



Cottua unoinatua, Reinhardt, Vid. Selsk. Natur. och Math. At'handl., 1833, 44. — GOnther, Cat. Fish. Brit. 



Mus.. ii. 172; Challenger Report, XXII, 1887, 62. 

 Centridermichthya undnaiua, Collect", Noisk. Nordh. Exped. Fisk. ,23. tal>. i. fig. 7; Forh. Vid. Selsk. Christ.. 



1880,14; Nyt Mag. I'. Naturvid.. XVIII, 1884,54. — LOtken, Kara-Havets Fisk. in Dijmphna-Togtet, 124. — 



LLLLJEBORG, Sverig. och Norg. Fisk., 161. 

 h i lut unoinatua, Kroyer, Nat. Tid., 1844, 253. — Jordan and Gilbert, Bull. xvi. U. S. Nat. Mus., 693. 

 Cottus bicornis, ReixhaRdt, hie. oil., vni. 75. 

 Artediellua uncinatus, Jordan, loc. <it. 



Body fusiform, its height contained 4J 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. Byes 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. vm, 13; A. 11. 



"An Arctic littoral species," writes Q-iinther, "more or less common in the sea between 

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



