266 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



GiUs 3 J or 4; slit behind tbe last gill small, or obsolete; gill-rakeis short, tnbeicle-like, or 

 obsok'te; gill-inembraiU'S broadly connected, often joined to the isthmus. Body naked, or 

 with scales, prickles, or plates, but never uniformly scaled. Lateral line simi)le. Dorsal 

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

 der, the soft ijart elongate, longer than spinous pt)rtion; caudal rounded; anal similar to 

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

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

 in all our species. Pyloric cieca usually in small number (l-S); 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 CoTTlNiE 



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 CottuS 



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

 Ujiper preopercular spine hooked, bifurcate. 



Body with some scales or plates Icklus 



Body naked Aktediellus 



Upper 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 Phionistius, Bean = EADULlNus, Gilbert 



II. Spinons-dorsal little developed, continuous with soft dorsal, tbe spines slender, concealed in the loose 



nakedskin; gill membranes broadly joined to isthmus; no slit behind last gill PsYcnROLUTiN.E 



A. Vomer and palatines toothless Psychrolutes 



B. Vomer with teeth. 



1. Gill membranes attached to isthmus. 



ti. Teeth on vomer and palatines. Dorsal continuous Cottunculus 



h. No teetli on vomer and palatines. Dorsal in two parts Mai-acocottus 



2. Gill membranes free from isthmus. 



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



COTTUS, Linnseus. 



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



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

 AcanthocoUu8, Girard, Smithsonian Contributions to Knowledge, iii, 1858. 



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

 sometimes embedded prickly plates, esiiecially 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 membranes forming a fold across the rather narrow isthmus; slit 

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

 ostegals mostly 0. Dorsal tins 2, sejiarate, the fii'st short, its spines rather slender; ven- 

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



Several species of this genus are foundat a depth of lOto 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, Kroy-er, Naturhist. Tidsskr., i, 253, 1844 (type, Icelua hamahia, Kroyer).- Gl^'THER, Cat. Fish. Brit. 

 Mus., II, 172.— Jordan and Gilbert, Bull, xvi, U. 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, 



