SALMONOIDE.E. 161 



total length including the caudal, or if the measurement be made from the knob of the lower 

 jaw to the tip of the central caudal rays, the head still constitutes one-fourth part. 



Teeth. — There are nine very strong and considerably incurved teeth in a row on each 

 intermaxillary, exclusive of four smaller ones which occupy the tip of the snout on both sides 

 of the principal row. The labials are closely set with much smaller teeth in a single series, 

 and the teeth on the limbs of the lower jaw are likewise close, numerous, and curved : those 

 on the dilated knob of the jaw are very much curved and are the largest of all, being upwards 

 of a quarter of an inch long. The palatine and vomerine teelh equal the posterior ones on the 

 lower jaw in size, and are implanted in double rows : there are none on the anterior knob of 

 the vomer. The tongue is long and narrow, and is armed with distant teeth on each side, 

 about the size of those on the labials. 



Gill-covers. — The posterior edge of the gill-cover is formed by the union of three small 

 segments of large circles. The operculum is strongly marked with lines which radiate from 

 its anterior upper angle : its lower edge slants downwards and forwards, so as to interpose 

 itself between the preoperculum and suboperculum. The latter forms an acute spherical tri- 

 angle, its convex side occupying nearly as much of the edge of the gill-cover as the operculum : 

 the borders of both these bones are finely radiated. The inter operculum is shaped much as 

 in other trouts, but its posterior angle reaches the edge of the gill-cover instead of being sepa- 

 rated from it by the suboperculum as usual. The preoperculum is broad, being at its greatest 

 width nearly equal to the operculum, and it is marked, as well as the adjoining part of the 

 interoperculum, with close raised lines and furrows, very different from the short diverging 

 tubular ridges of this bone in other trouts. The bones of the head, in general, have an un- 

 usually fibrous texture. Gill-rays flat, but narrower and shorter than in most other species : 

 the longest are the central ones under the articulation of the jaw, the more posterior ones being 

 a little shorter : there are 12 on the right side and 13 on the left. 



Fins.— Br. 12—13; P. 16; D. 14—0; V. 11 ; A. 17; C. \%. 



The pectorals contain sixteen rays ; the dorsal fourteen, the height of the fourth, fifth, or 

 sixth, which are the longest, equalling the length of the attachment of the fin. The adipose 

 fin is opposite to the three last rays of the anal. The ventrals are under the ninth, tenth, and 

 eleventh dorsal rays. The ventral appendages are long, reaching to within one-third of the 

 tips of the fin. The anal contains seventeen rays, the first one short, and the second nearly 

 equalling the third, which is the longest ; the last one is half as long as the third. The caudal 

 fin has an unusually tapering base, and is forked at the end, the depth of the fork being half 

 the length of the central rays ; it contains nineteen rays exclusive of nine short basal ones 

 above and below. 



The Scales are small and vary in form, some being oval, others four-sided with the corners 

 rounded. They are most regular and closest on the tail, being in contact but not tiled : on 

 the anterior part of the back they are separated by spaces equal to their own breadth, but on 

 the sides they are not so far apart. Under the dorsal fin, and near the lateral line, a linear 

 inch includes eleven scales, the intervening spaces occupying about one-third of the inch. 

 There are 170 scales on the lateral line, and 70 in a vertical row anterior to the ventrals, of 



Y 



