148 TELEOSTEI: ACANTHOPTEEI. — XX. 



Arctic fishes, numerous, 35 to 50. Genera 40; species 150, mostlj- 

 of the springs, rock-pools, and seashores of Arctic regions ; a few in 

 the deep sea. Singular fishes, mostly of small size, and of little 

 value as food. The fresh-water species are very destructive to 

 eggs of other fishes. 



w. Spinous D. longer than soft part, of more than 14 spines. (Semitrip- 

 terince.) 

 b. Spinous D. deeply notched, the anterior spines highest; skin with prickles 

 and warts ; teeth on vomer and palatines ; gill membranes free from 



isthmus; no slit behind last gill Hemitripterus, 186. 



aa. Spinous D. shorter than soft part, of less than 13 spines; dorsal spines not 

 concealed ; gill openings not very small. V. present. {Cottinw.) 

 c. Vomer with teeth. 

 d. Slit behind last gill obsolete or reduced to a round pore; skin with- 

 out true scales. 



Gill membranes broadly united to the isthmus, not forming a fold 

 across it; head feebly armed; palatine teeth few or none. 



COTTUS, 187 

 ee. Gill membranes free from isthmus or else forming a broad fold 

 across it; head well armed. 

 y. Palatine teeth none ; skin naked or prickly. 



ACASTHOCOTTUS, 188. 



^ff". Palatine teeth well developed; skin smooth. 



Aetediellus, 189. 

 dd. Slit behind last gill small, but evident; no palatine teeth. 



g. Skin smooth; gill membranes not quite free from isthmus; 

 preorbital, etc., strongly cavernous. . Triglopsis, 190. 

 gg. Skin with minute prickly scales, and with plates along back 

 and lateral line ; gill membranes free from isthmus. 



Teiglops, 191. 

 CO. Vomer without teeth; preopercular spine antler-like; a fold across 

 isthmus and no slit behind last gill ; no scales. 



Gymnacanthus, 192. 



186. HEMITRIPTERUS Cuvier. (fnu-, half ; rpe'is, three ; 

 TTTtpov, fin.) 



404. H. americanus (Gmelin). Sea Raven. Head large, 

 with many humps and ridges above. Brown, body and fins much 

 variegated with blackish. Head 2f ; depth 3|. D. IV, XII, 1,12. 

 A. 13. Lat. 1. 40. L. 18. Cape Cod to Arctic Sea. 



187. COTTUS (Artedi) Linna;us. ( f/ranidea DeKay.) Miller's 

 Thumb. (Ancient name of C. gobio, from kottos, head.) 



i». Palatines with teeth; ventrals I, 4 (the spine obscure). 

 b. Preopercular spine large, as long as eye, strongly hooked upward ; skin 

 above with coarse prickles ( Taurldea Jordan & Hice). 



405. C. ricei Nelson. Head broad, body contracted at base of 

 tail. Olivaceous, finely speckled. Head 3| ; depth 5 J. D. VIII -17. 

 A. 12. L. 2^. Lake Mich, and L. Ontario, rare. (To Frank L. 

 Rice.) 



