192 NORTHERN ZOOLOGY. 



DESCRIPTION 

 Of a specimen from Great Bear Lake, latitude 65° N. 



Colour. — Back dark ; sides of a hue intermediate between lavender-purple and bluish- 

 grey ; belly blackish- grey with several irregular whitish blotches. There are five or six 

 quadrangular spots of Prussian-blue on the anterior part of the body, each tingeing the margin 

 of four adjoining scales. The head is hair-brown above, the cheeks and gill-covers the same, 

 combined with purplish tints, and there is a blue mark on each side of the lower jaw. The 

 dorsal fin has a blackish-grey colour, with some lighter blotches, and is crossed by rows of 

 beautiful Berlin-blue spots ; it is edged with light lake-red. The ventrals are streaked with 

 reddish and whitish lines in the direction of their rays. 



Scales covered with a thickish epidermis and consequently having little lustre; they are 

 semi-oval, their exterior edges being a segment of a circle, and appearing under a lens finely 

 but irregularly toothed or serrated : their bases are truncated, and show three lobes or teeth 

 corresponding with four deep grooves that converge in the middle of the scale : the fine con- 

 centric lines of structure are waved. The scales are smaller on the forepart of the back 

 and belly: on the sides they measure four lines transversely, and rather less from their 

 exterior edge to the base. There are 87 on the lateral line, including three or four small 

 ones on the base of the caudal, and 27 in a vertical row anterior to the ventrals, of which nine 

 are above the lateral line. The scales do not end on the caudal as in the trouts, lavarets, 

 &c, but extend farthest on the lobes, having the same forked termination with the fin itself. 

 In this respect, and in the roughness of the scales, the Graylings have an analogy with the 

 Percoidece and other rough-scaled fishes. The lateral line is straight, and the scales com- 

 posing it, though of equal size with the others, show only half as much surface when in their 

 place. 



Form. — Body compressed with an elliptical profile, the head, when the mouth is shut, 

 ending acutely, but when viewed from above, or in front, the snout is obtuse. The greatest 

 depth of the body is scarcely one -fifth of the total length, caudal included. Head small, 

 being one-sixth of the total length, excluding the caudal, or one-seventh including it. In the 

 dried specimen there is a slightly-elevated sagittal ridge, the occiput is radiated, and the 

 tubular lateral ridges extend conspicuously from the nostrils to the upper angle of the gill- 

 cover. A line of tubes also passes along the middle of the infra-orbitar bones, another down 

 the upper limb of the preoperculum, and there are three diverging tubes on the lower limb of 

 that bone. Orbit large, distant half its own diameter from the tip of the snout, and two dia- 

 meters from the edge of the gill-cover. Nostrils midway between the orbit and tip of the 

 snout. The infra-orbitar bones consist of four distinct radiated ones behind the eye, a narrow 

 tubular ridge beneath the orbit, and a small thick plate with diverging tubular lines before 

 the eye. Mouth not cloven as far back as the edge of the orbit. Intermaxillaries narrower 

 and longer than in the coregoni, but overlapping the articular ends of the labials less than in 

 the truttce. Labials thin elliptical plates, the posterior piece lanceolate and as broad as the 

 anterior one. Under jaw tolerably strong and rounded at the tip, which, when depressed, 

 projects about four lines beyond the snout. 



