SALMONID^E. 89 



equal to about tlie length of tlie snout. During the breeding season a knob 

 frequently exists at tlie upper side of the anterior end of the lower jaw in the 

 males. The posterior extremity of the upper jaw reaches to beyond the hind 

 edge of the eye in full-grown examples, and it is stronger in some varieties than 

 in others. Tlie form of the gill-covers in this fish has been held to almost denote 

 species with some authors, to be dependant on sex according to others, or to be of no 

 signification at all. In some, as the typical S. trutta (see plate cxi), the posterior 

 edge of the preopercle is somewhat sinuous, while it has a distinct lower limb: 

 in the sewin this latter is less distinctly marked (plate cxii), but in the white 

 salmon, or herling, there is hardly a trace of it ; but, however, every intermediate 

 form may be found, or they may even differ on the opposite sides of the head in 

 the same specimen. The posterior edge of the opercle and subopercle form a 

 semi-circle, in which the subopercle generally, but not invariably, forms the most 

 prominent point. Several raised and curved lines are mostly present upon the 

 outer edge of the subopercle and opercle. Teeth — -in the young similar to those 

 in the salmon fry : there is a double row along the body of the vomer and a 

 transverse row where it joins the palatines. At an early age these vomerine teeth 

 become lost more quickly in s.mie examples than in others, but generally there is 

 only a single row in examples a foot or upwards in length : the example in plate cxi, 

 which was 14 inches long, had a double row of six teeth on the vomer, besides a 

 transverse row of four anteriorly. The teeth in the jaws and palatines in a single 

 row. Three to six strong*, sharp recurved ones on either side of the tongue. 

 Fins — in large examples the fins are comparatively shorter than in smaller ones, 

 and the pectoral rarely extends half-way to the base of the ventral, which latter 

 is situated beneath the middle of the dorsal. The dorsal fin is comparatively 

 small : while the caudal is subject to considerable diversities of form, in large fish 

 being mostly almost square at its posterior extremity, or it may be notched, or 

 should the ends of its lobes be drawn asunder, it appears to be lunated. Sea les — ■ 

 14 or 15 row T s in an oblique line from the hind edge of the adipose dorsal fin, 

 downwards and forwards to the lateral-line. The scales in this species, more 

 particularly in the young, are very deciduous. Ccecal appendages vary considerably 

 in number, and though I am satisfied that their enumeration recorded as existing 

 in the British Museum specimens is correctly recorded in the Catalogue, I find 

 reason to believe a much wider difference can be found in nature. Mr. Brotherton, 

 of Kelso, sent me in August a fine specimen from the Tweed, termed "bull- 

 trout" (similar externally to the figure in plate cxi, fig. 2), it was a female, with 

 small ova, only two teeth remained on the forepart of the vomer, its tail was 

 ;il most square at its extremity, and it only possessed 33 ccecal appendages. 

 Colours — Back bluish gray, becoming lighter on the sides and beneath, having 

 a purplish gloss when in the highest condition, but which takes on a muddy hue 

 after having been some time in fresh water. Small black spots, mostly of an 

 X-shape, exist along the gill covers and upper two-thirds of the body, or merely 

 uiimi tlie upper half of the gill covers, where they may be surrounded by a light 

 margin, while on the bod}- they frequently are not seen below the lateral-line. 

 Some are densely, others sparsely spotted, with every intermediate variety. The 

 dorsal tin similarly may be destitute of spots, thickly or thinly covered by them. 

 Pectoral of a bluish lilac, often darkest externally. Caudal gray, or even dark 

 coloured. I hiring the spawning season the head of the male is of an olive brown, 

 and the body of a dingy orange, or reddish brown, while the female is of a 

 blackish gray. Thompson alludes to one example which had a series of deep 

 orange longitudinal stripes, probably a male in the breeding livery. Purr or 

 Orange fins are marked almost similarly to the young of the salmon, but the dorsal 

 lin has generally a white upper edge anteriorly, with a black basal band, which 

 often passes along almost the entire extent of the upper fifth of the fin, and 

 similar to the colours seen in the brook-trout. In the grilse state the caudal is 

 usually blackish. 



Vari ties —These arc referred to under the head of Salmo albus (page 85), and 

 fif. cambricus (page 87): while the Eresh water forms will be discussed under 

 N. levenensis (page '.':'>), and S.fario (page '.'-"'I. 



