140 NORTHERN ZOOLOGY. 



the preceding names : but to serve as an explanation of plates 91 and 92, and also 

 as an introduction to the descriptions of the American trout, I shall give a few 

 notices of the British ones that I have had an opportunity of examining. Of the 

 correct designation of our most important trout, 



1. Salmo salar there can be no doubt. The head of a " run fish," or of one taken on 

 its way to the sea after spawning, is represented on Plate 91, f. 1. The posterior edge of the 

 gill-cover is the segment of a circle, into the formation of which the suboperculum enters 

 largely, and there is but one tooth on the vomer. The specimen was taken in the Water of 

 Urr, a river of Galloway, in the month of December : some other particulars respecting it, will 

 be found in our account of the Quebec Salmon. Mr. Yarrell informs me that the Common 

 Salmon has 60 vertebrae in the spine *. The number of pyloric caeca appears to vary. The 

 gentleman just mentioned having sent me the viscera of two large female salmon, brought to 

 the London market, in prime condition, in the month of April, I found 63 caeca in the one, 

 and 68 in the other. The gut and larger caeca of the former were filled with botriocephali, 

 the roe was about one-third grown : the latter, which was not quite so far advanced towards 

 the spawning state, was not infested with tape-worm : the alimentary canal of both was 

 thickly lined with a tenacious mucus, mixed with some specks of a red matter resembling 

 lobster spawn. 



2. Salmon-trout. Under this name a fish is brought in large quantities to the London 

 market in the beginning of summer. It has a very close resemblance to the Common salmon, 

 of the same size, but has nevertheless an aspect so peculiar as to be readily recognised by the 

 fishmongers. Its head is proportionably somewhat larger than that of the salar, but its 

 vomerine teeth are nearly the same, that is, they vary in number from one or two to five or 

 six, and are placed, in the latter case, two in front, the others in a single row, but turned 

 alternately to opposite sides. The teeth generally are more slender and acute than those of 

 the Common salmon. The gill-cover differs from that of the latter in the curve of its pos- 

 terior edge being elliptical, in consequence of the suboperculum being much less rounded off. 

 According to Mr. Yarrell, the Salmon-trout has only 59 vertebrae, or one fewer than the S. 

 salar. One specimen from the Nith had 59 caeca, another 61. The head of the latter is 

 represented in Plate 92, f. 1, A, with a view of its open mouth (f. 1, B), to show the denti- 

 tion. The scales of the Salmon-trout are thin and delicate, and the spots on the sides have 

 sometimes a slender crescentic form ; at other times they assume the shape of two crescents 

 turned back to back, or that of the letter x. I have obtained specimens from Loch Stennis, 

 in the Orkneys, from the rivers Nith and Medway, and from Wales. In the latter quarter it 

 is confounded with another species, under the name of Sewin. It feeds more upon fish than 

 the Common salmon f. I took a young coal-fish and a fragment of sand-stone from the 



* Aitedi says of the Common salmon of the Baltic {Lax Suecorum"), " Vertebra in universum quinquaginta sex." 

 f Lieuteuant-Colonel Lawrence, an ardent and experienced angler, informs me that the salmon is more in the habit of 

 springing out of the water than the Salmon-trout, and will do so either to take the artificial fly, or to disengage itself from 

 the hook when it feels the smart ; but the Salmon-trout, as soon as it is struck by the angler, descends directly to the bot- 

 tom of the pool, and can scarcely be dislodged. 



