salmonoidejE. 209 



Attihawmeg and Namaycush differ from the Herring- Salmon in resorting to the 

 greatest depths of the lake in the winter, and it may be here observed, that fish can 

 receive a free supply of fresh air during that season, even in the centre of the most 

 extended lake, through the Avide rents caused by contraction of the ice at low tem- 

 peratures. Warmer weather causes the ice to expand again, and great blocks of it 

 are then forced up through the crevices, so as to form walls sometimes twenty feet 

 in height. The memoranda of various particulars respecting the habits and ana- 

 tomical structure of the Herring-Salmon, that I made during our residence on 

 Great Bear Lake, were lost in the struggle that we had subsequently with the 

 Esquimaux, and at this distance of time I cannot supply the loss from memory. 



DESCRIPTION 

 Of a specimen taken in Great Bear Lake. 



Form in profile closely resembling the Round-fish, but the body is much more compressed, 

 and the head larger, being one-fifth of the length between the tip of the snout and end of the 

 scales on the caudal, and nearly equal to the greatest depth of the body. In the dried speci- 

 men, the breadth of the nape equals the distance between the supra-orbital plate of the frontal 

 bone and the articulation of the lower jaw, and the width between the upper ends of the 

 labials is twice as great as in the Round-fish. The sagittal ridge rises into an acute crest 

 from the nape to the nostrils, and the tubular ridges on the frontal bone and anterior sub- 

 orbital, are more conspicuous than in any of the preceding species. The orbit is situated the 

 length of its diameter from the end of the snout, and thrice as far from the edge of the gill- 

 cover. The orifice of the mouth is large in comparison with that of the other coregoni, equal- 

 ling the orbit in diameter : when the jaws are extended, the intermaxillaries are brought into 

 a line with the forehead, instead of dropping vertically as in the Round-fish. The labials are 

 large, and have a widely oblong form, carrying their breadth close to both extremities ; their 

 tips, when the mouth is shut, reach as far back as the centre of the orbit ; the anterior piece 

 is traversed by an obtuse keel, and the posterior one is only half as long, and less than half 

 as wide as the anterior one. There are no teeth. Gill-covers. The preoperculum is broader 

 than usual, particularly its upper limb : there are four conspicuous tubular rays on its lower 

 limb. The interoperculum is large, being bigger than that of the Attihawmeg. The posterior 

 margin of the gill-cover is uneven or slightly lobed. 



Fins.— Br. 8—8; D. 14—0; P. 19; V. 11 ; A. 14; C. 19|. 



The eighth ray of the dorsal, the first of the ventrals, and the thirty-third scale of the 

 lateral line, are situated midway between the tip of the snout and end of the scales on the 

 caudal. The ventral appendages are slender and unusually long. The adipose is about its 

 own breadth posterior to the anal, which is smaller than in the Attihawmeg. The caudal is 

 deeply forked. 



Scales transversely oval, considerably larger than those of the Round-fish, but smaller 

 than those of the Attihawmeg ; one from the side measures five lines vertically, and four 



2e 



