COTTIDJE ICELUS. 691 



1O1. I. hamatus Kroyer. 



Yellowish, with many brown spots. Head large, naked ; upper pre- 

 opercular spine small, hooked upwards, bifurcate; 3 spines below it, two 

 of them hooked upwards; two blunt occipital spines; vertex depressed. 

 Skin of body above with warty scales and small prickles; some rows of 

 bony scales from neck to base of caudal; a series of tubercles along 

 lateral line; sides of body with scattered scales; interocular space 

 very narrow, its width 4 in eye; dorsals separated; pectorals shorter 

 than head; no air-bladder; gill-membranes broadly joined, free from 

 isthmus; no slit behind last gill. D. IX-20; A. 16; V. I, 3. Arctic 

 Seas, Alaska to Spitsbergen. 



(Kroyer, Naturhist. Tidsskr. i, 253, 1844; Giinther, ii, 172.) 

 dd. Upper preopercular spine long, with 5 hooked processes. 



1O49. I. qiiadrisersatais (Lockington) J. & G. 



Pale olivaceous, somewhat mottled; lateral line with dark blotches; 

 branchiostegal region black in the males ; a black bar at . base of 

 caudal; a black spot at front of spinous dorsal, and one at tip of the 

 last spine; pectorals with a dark spot at base; other fins olivaceous, 

 little variegated. Body slender, little compressed, tapering from the 

 shoulders to the slender tail. Mouth moderate, the maxillaries reach- 

 ing about to middle of pupil; a pair of ridges on the occiput, each 

 ending in a spine, the space between them concave; interocular space 

 very narrow, grooved; upper preopercular spine very long, armed with 

 about 5 hooks, all but one directed upwards; below this three simple 

 spines. Head naked or very nearly so, with conspicuous mucous pores 

 above and a few minute cirri. Dorsal fins separated; pectorals broad, 

 about reaching anal; ventrals very small. Lateral line with a series of 

 spinous plates; above it along the back a double series of spiuous 

 plates placed at an angle, the upper plates with the free edge down- 

 ward and backward, the lower plates with the free edge upward and 

 backward; this band composed of a single series before and behind, 

 and not extending around the dorsal in front; skin otherwise perfectly 

 smooth. Head 3^; depth 5. D. VIII-13; A. 12; V. I, 3. L. 3 inches. 

 Deep waters off San Francisco; locally very abundant. 



(Artedlus quadriseriatus Lockington, Proc. U. S. Nat. Mus. 1879, 330.) 



aa. Spiuous dorsal fin deeply emargiuate; head scaly. (Cliitonotus* Lockiogton.) 



* Lockington, Proc. U. S. Nat. Mus. 1881, 141 : type Chitonotus megacephalus Lock. 

 , a rough cloak; r&ro?, back.) 



