Fishes. 4783 



these are ten or twelve in number. I have also examined a large 

 Thames trout, weighing 5|-lbs. ; it has a double row of teeth on 

 the body of the vomer, and a group of perfectly distinct teeth on the 

 chevron of the vomer. There is the skeleton of a very large river trout 

 in the College of Surgeons, in London ; the specimen is not favorably 

 placed for the examination of this question, but so far as I can 

 observe, the teeth are arranged as in the Kennett trout : thus, contrary 

 to M. Valenciennes' view, these species of trout are not characterized 

 by the absence of the anterior group, but, by the presence of a 

 double row on the body of the vomer, which 1 have found to 

 apply to all trout ; all are characterized by a double row of teeth 

 on the body of the vomer, but as regards the transverse or ante- 

 rior teeth, some lose them and some do not; the river trout seem 

 to retain them to the last, and M. Valenciennes admits that they are 

 present in the beautiful trout of the Moselle, that species which 

 he assumes as the type of his genus Salmo Trutta. Here is the 

 description of the dentition of the trout of the Moselle by M. Valen- 

 ciennes himself : " II en existe un seul rang, sur chaque palatin et 

 celles de vomer disposees sur deux rangs, sont divergentes aussi meme 

 plus fortes; aussi une petite rang transversale sur le chevron."* 

 The trout of Baillon, which M. Valenciennes at first mistook for a sal- 

 mon, until put right, as he admits, by the fishermen, has a double row 

 of teeth on the body of the vomer, and a complete set of transverse 

 teeth. Now this determination he arrived at from the examination of 

 a young fish 13j inches long; but with years, the trout of Baillon 

 may lose some of these teeth and assume a different character ; in as far, 

 then, as regards the dentition of a Baillon trout of 13J inches, the fish 

 might be either a common river trout, a sea trout, or a salmon, for at 

 that age the dentition is nearly identical in all; and thus the sub- 

 family to which the Baillon trout belongs has not been determined by 

 M. Valenciennes, and cannot be by his method in a fish of the size 

 quoted. 



On the other hand, in certain large lake trout, reported to me as 

 from Ireland, the anterior cluster of vomerine teeth was absent or had 

 disappeared, there remaining on the body of the vomer a double row 

 of teeth : these trout were of great size : now this is the dentition 

 which corresponds to M. Valenciennes' idea of a real trout, but 

 we have seen that it does not apply to any river trout I have yet ex- 

 amined, nor to those of France, nor even rigorously to the celebrated 



* Page 321, 8vo edition. 



