ADDENDA. 309 



Page 183. Salmo Mackenzii. 



Having received several heads of this fish through the kind attentions of Mr. 

 King, who accompanied Captain Back on his recent expedition, I have been 

 enabled to give a view of the teeth in plate 94, f. 1. 



All the teeth are en velours, the band on the intermaxillaries and end of the lower jaw is 

 very narrow, that on each palate bone is broader and unites before with a pretty large circular 

 patch on the anterior extremity of the vomer. The greater part of the surface of the tongue 

 is covered with teeth, though its tip is smooth. The labials and sides of the lower jaw are 

 perfectly toothless. The posterior piece of the labial is widest above, tapering gradually to 

 an acute point, which is even with the extremity of the anterior piece, and its length is about 

 two-thirds of that of the latter. The under jaw is shorter than the upper surface of the head. 

 The rays of the gill-membrane vary from nine to ten on the right side, and from ten to eleven 

 on the left, there being generally, though not always, one more of the latter. 



Page 201. Salmo (Coregonus) tullibee. 



The acquisition of a specimen of the Tullibee from Albany District, Hud- 

 son's Bay, enables me to make some essential additions to the description of 

 that fish. 



In external appearance, and especially in the size and lustre of the scales, the Tullibee cor- 

 responds with the group of Coregoni, named Salmon-herrings, and bears the strongest resem- 

 blance to C. lucidus, p. 207, pi. 90, f. 1. The depth of the body is, however, greater than in 

 that species, and the scales are so tiled, that the uncovered portion measures considerably 

 more vertically than longitudinally. The posterior piece of the labial is likewise wider, and 

 the suboperculum has a fuller, though rounded exterior edge, giving the gill-plate more the 

 form of that of C. albus, pi. 89, f. 2. The greatest depth of the considerably-compressed 

 body is equal to one-fourth of the total length, caudal included; while the head forms a fifth 

 part of that length. The under jaw protrudes rather more beyond the upper one than in 

 C. lucidus. The lateral line contains eighty-one scales, whose tubular ridges are curved 

 downwards more conspicuously than in other species. There are twenty-three scales in a 

 vertical row under the first ray of the dorsal, a linear inch measured in that direction contain- 

 ing four scales in situ, or rather more than seven in a longitudinal direction. The first ray 

 of the ventrals and fifth of the dorsal is opposite to the thirty-first scale of the lateral line, 

 -vhich is exactly midway between the tip of the snout and end of the scales on the caudal. 



Fins.— Br. 8—9 ; P. 16; D. 15—0; V. 12; A. 14 or 15; C. 19f. 



