2G6 DEEP-SEA FISHES OF THE ATLATs'TIC BASIN. 



Gills 3 J or 4; slit behind the last gill small, or obsolete; gill rakers sliort, tubercle-like, or 

 obsolete; gill-iiieinbraues broadly conuected, often Joined to tlie istliiiius. Body naked, or 

 with scales, prickles, or plates, but never uniformly scaled. Lateral line simple. Dorsal 

 fins separate or somewhat connected, the spines less than thirteen in number, usually slen- 

 der, the soft part elongate, longer than spinous portion; caudal rounded; anal similar to 

 soft dorsal, spineless; pectorals large, with broad, procurrent bases; ventrals thoracic 

 (rarely entirely wanting), the rays usually less than i, 5. Pseudobranchia- present, at least 

 in all our species. Pyloric cibca usually in small number {i-8); air-bladder commonly 

 wanting. 



KEY TO THE DEEP-SEA GENERA. 



I. Spinous dorsal not concealed. 



A. Gill openings extending below at least to the base of the lowest pectoral ray C0TTIN.E 



1. Slit behind last gill obsolete. 



a. Gill membranes free from isthmus, or else forming a broad fold across it; head well armed. 



Palatines toothless. No true scales on body C'ottus 



Palatines with well-developed teeth. Body more or less scaly. 

 Upper preopercular spine hooked, bifurcate. 



Body with some scales or plates Icelus 



Body naked Artediellus 



tJpi)er preopercular spine with 3-5 hooked jirocesses Icelinus 



2. Slit behind last gill evident. 

 Palatines toothless. 



Gill membranes free from isthmus ; series of plates along back and along lateral line. 



No plates on head ; space between lateral plates prickly Tkiglops 



Plates on snout and operiles Prionistits, Bean = Eaduunus, Gilbert 



II. Spinous-dorsal little developed, continuous \\ith soft dorsal, the spines slender, concealed in the loose 



nakedskin; gill membranes broadly joined to isthmus; no slit behind last gill PsYCHKOLUTiNiE 



A. Vomer and palatines toothless Psychrolutes 



B. Vomer with teeth. 



1. Gill membranes attached to isthmus. 



a. Teeth on vomer and palatines. Dorsal continuous Cottunculus 



6. No teeth on vomer and palatines. Dorsal in two parts Maiacocottus 



2. Gill membranes free from isthmus. 



a. Vomerine teeth in two patches, none on palatines. Dorsal in two parts [Dasycottus] 



COTTUS, Linnasus. 



Coitus, ItmtfMVS, Syst. Nat. Ed., x, 1758, i, 207, ed. 2, 1766, 1,451.— GtJNTHER, Cat. Fish. Brit.Mus. 11, 155.— 



Jordan and Gilbert, Bull, xvi, U. S. Nat. Mus., 700. 

 AcanthocottHS, Girard, Smithsonian Contributions to Knowledge, III, 1858. 



Cottids with body rather slender, subfusiform, covered with thick skin, in which are 

 sometimes embedded prickly plates, especially along lateral line; deciduous granular tuber- 

 cles also sometimes present, but no true scales. Head large. Mouth terminal, large, the 

 lower jaw included; villiform teeth on the jaws and vomer, none on the palatines; sub- 

 orbital stay strong; preopercle with 2 strong straight spines above, directed backward, and 

 1 below, directed downward and forward; opercle, nasal bones, orbital, rim, and shoulder 

 girdle usually armed; gill mendn-anes forming a fohl across the rather narrow isthmus; slit 

 behind last gill small or wanting, often reduced to a mere pore; vertebriB about 28. Branchi- 

 ostegals mostly G. Dorsal fins 2, separate, the first short, its spines rather slender; ven- 

 tral rays usually i, 3. — {Jordan and Gilbert.) 



Several species of this genus are found at a depth of 10 to 15 fathoms on c ir New England 

 coast. None have, however, been taken below the 100-fathom line, saving C. bathybius, 

 Giinther, from south of Yeddo, Japan. 



ICELUS, Kroyer. 



Icelus, Kroyer, Naturhist. Tidsskr,, i, 253, 1S14 (type, Icclun hamatus, Kroyer).— Gunther, Cat. Fish. Brit. 

 Mus., II, 172.— Jordan and (Jilbkrt, Bull, xvi, IT. S. Nat. Mus , 689. 



Cottids with body fusiform, covered with rough scales or plates. Mouth rather large; 

 teeth on vomer and palatines. Head naked, usually with cirri ; preopercular spine hooked. 



