50 AMERICAN FISHES. 



by the different formation of his gill-covers, and the convex form of 

 his caudal fin, whence he is said to be termed the Round-tail in the 

 river Annan, in Scotland. This fish is unknown in America, and is 

 merely mentioned for the sake of example and illustration. 



In the Salmon Trout of Great Britain, Salmo Trutta Lin., a mi- 

 gratory fish, growing to a very large size, the teeth extend nearly the 

 whole length of the vomer, thereby establishing a distinction between 

 this and the two aforenamed species. 



Of the common Trout, we have already seen the dental arrange- 

 ment. In the two distinct varieties of Lake Trout, recognised by 

 authorities in Great Britain, which are non-migratory, and analogous 

 to our Lake Trout ; viz 



In the Great Gray Trout, or Loch Awe Trout, Salmo Ferox, which 

 is common to most of the large Scottish and Irish inland waters, and 

 which is pronounced by Mr. AGASSIZ to be distinct from any of the 

 continental Lake Trout, these teeth extend along the whole length of 

 the vomer. 



And in the Lochleven Trout, Salmo Levenensis, sive Ccecifer, WALK- 

 ER and PALMER, if it be a distinct species from the common Trout, 

 Salmo Farioj as appears to be conceded although I must say I doubt 

 it, as I do the Gillaroo, which, however, is more doubtful there are 

 thirteen teeth on the vomer, extending through its whole length. 



It would be well, indeed, if American anglers would take a little 

 pains about the examination of these points, and would note them down 

 in their tablets -in which, doubtless, they insert the weight of their 

 captives together with the relative proportion of the length of the 

 head to that of the entire body ; the form of the gill-covers ; and rela- 

 tive position of the eye to a line drawn from the front teeth to the 

 lower posterior angle of the operculum or suboperculum, as it may be ; 

 the number of rays in each of the several fins ; and especially the form 

 of the caudal fin-tail whether forked, concave, square, or convex. 



A very few memoranda on such points as these, accurately recorded, 

 and assisted, where practicable, by the roughest sketch, would be of 

 greater utility to the cause of science, than can be readily imagined ; 

 and we should undoubtedly soon arrive at facts of great importance, 

 and perhaps discover some new and interesting species of this most 

 interesting family. 



