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, (Hemitrip- 
tering.) 
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. . . . . Hkmirrirrerus, 186. 
aa, Spinous D. shorter than soft part, of less than 13 spines; dorsal spines not 
concealed; gill openings not very small. Y. present. ( Cottine.) 
vc. 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. 
Cortus, 187. 
ee. Gill membranes free from isthmus or else forming a broad fold 
across it; head well armed. 
J. Palatine teeth none; skin naked or prickly. 
ACANTHOCOTTUS, 188. 
Jf. Palatine teeth well developed; skin smooth. 
ARTEDIELLUS, 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. . TriGxopsis, 190. 
gg- Skin with minute prickly scales, and with plates along back 
and lateral line; gill membranes free from isthmus. 
Trictops, 191. 
ec. Vomer without teeth; preopercular spine antler-like; a fold across 
isthmus and no slit behind last gill; no scales. 
Gymnacantuus, 192. 
186. HEMITRIPTERUS Cuvier. (jyt-, half; rpeis, three; 
mrepor, fin.) 
- 404. H. americanus (Gmelin). Sta Raven. Head large, 
with many humps and ridges above. Brown, body and fins much 
variegated with blackish. Head 22; depth 33. D. IV, XII, 1,12. 
A. 13. Lat.1.40. L.18. Cape Cod to Arctic Sea. 
187. COTTUS (Artedi) Linneus. (Uranidea DeKay.) MiLiEr’s 
Tuums. (Ancient name of C. gobio, from korres, head.) 
a. Palatines with teeth; ventrals I, 4 (the spine obscure). 
6. Preopercular spine large, as long as eye, strongly hooked upward; skin 
above with coarse prickles (Tawridea Jordan & Rice). 
405. C. ricei Nelson. Head broad, body contracted at base of 
tail. Olivaceous, finely speckled. Head 32; depth 5}. D. VIII-17. 
A.12. L. 24. Lake Mich. and L. Ontario, rare. (To Frank L. 
Rice.) 
