148 TELEOSTEI: ACANTHOPTERI. — XX. 



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

 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. 



a. Spinous D. longer than soft part, of more than 14 spines, (ffemitrip- 

 terituB.) 

 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. (Cottince.) 

 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. 

 f. Palatine teeth none ; skin naked or prickly. 



ACANTHOCOTTUS, 188. 



ff. Palatine teeth well developed; skin smooth. 



Artediellus, 189. 

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



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

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

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

 and lateral line ; gill membranes free from isthmus. 



Triglops, 191. 

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

 isthmus and no slit behind last gill ; no scales. 



GYMN ACANTHUS, 192. 



186. HEMITRIPTERUS Cuvier. (^"-, half; rpels, three; 



7TT(f}6v, fin.) 



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

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

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

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



187. COTTUS (Artedi) Linnaeus. (JJranidea DeKay.) Miller's 

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



a. 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 {Tauridea Jordan & Rice). 



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

 tail. Olivaceous, finely speckled. Head 3| ; depth b\. D. VIII -1 7. 

 A. 1 2. L. 2\. Lake Mich, and L. Ontario, rare. (To Frank L. 

 Rice.) 



