SALMO TRUTTA. 311 



he describes from the Esk in Cumberland ; and that in the Grilse condition it 

 is known in Scotland as the Phinoc. It is also known in Scotland by various 

 local names, such as, Hireling 1 , Whiting, and Black Tail. 



The Salmon Trout grows to a length of three feet, .but the female becomes 

 mature when ten or twelve inches long. The head of ' the fish is rather deep 

 as compared with its length, and slightly exceeds the greatest depth of the 

 body. It is about two-ninths of the total length of the fish, though in old 

 males it may be one-quarter of the length, owing to the increased development 

 of the jaw-bones, and the hook of the lower jaw. The snout is elongated, so 

 that the upper profile of the head is sometimes concave. The maxillary bone 

 is longer than the snout, and does not extend far behind the orbit. The inter- 

 orbital space is convex, and as wide as the snout is long. The hinder oper- 

 cular margin is obtusely rounded, but with the sub-operculum projecting a little 

 backward. The pre-operculum has a distinct lower limb. 



The head of the vomer is triangular, as broad as long, and toothless. The 

 body of the bone has a longitudinal ridge, along which is a single series of teeth, 

 some of the hinder of which diverge outward alternately to each side. Von 

 Siebold and Dr. Giinther state that most of these teeth are lost successively at 

 different ages; often only three or four are left in specimens a foot long, while 

 sometimes six or eight teeth may remain in specimens twenty inches long, but 

 in larger specimens still only two or three teeth in front are found. 



In all these characters the Salmo trntta agrees with the Grey Trout, Salmo 

 eriox, of the Tweed and the Forth, and we are unable to discover any sufficient 

 specific character to separate the latter, which is the S. brackypoma of Giinther, 

 from this type. The posterior margin of the caudal fin may be rounded in 

 old specimens, truncate, or slightly emarginate, or deeply forked in the young ; 

 but all the fins are short, especially the caudal and pectoral. Both the dorsal 

 and anal fins are as high as long. There are fourteen or fifteen scales in a 

 transverse series, running from behind the adipose fin forward to the lateral 

 line, a character which this species shares with S. cambricus, S. brackypoma, 

 and other forms. The scales are short, thin, and rounded. The upper parts 

 of the body are blackish, usually with a purplish tinge on the silvery sides, 

 and the under part of the body is silvery. There are generally X-like spots, 

 which may be numerous or few, and there are commonly small round black 

 spots on the sides of the head and dorsal fin. When unspotted it is the 

 Sllberlachs of the Germans, and Salmo albiis of some British writers. Each 

 scale is frequently surrounded by minute black dots. In the young state 

 there are nine or ten dusky transverse bars, but as the Parr changes to the 

 Grilse they become lost. When young it often has orange or red spots on the 

 sides, and the Bull Trout Parr of the Tweed is sometimes called ' ' Orange Fins." 



