2\6 Field and Forest Rambles. , 



In the first place, the outlines of the gill covers of allied 

 species with which it is at all likely to be confounded, show, 

 for example, as regards the salmon (S. salar), on the preceding 

 page, that the posterior point of juncture between the oper- 

 culum (p) and the sub-operculum (s) is about half-way between 

 the upper end of the gill opening and the lower angle of 

 the sub-operculum in the salmon, whereas in the silvery- 

 salmon trout and sea trouts it is nearer to the lower angle 

 of the sub-operculum than to the upper end of the gill open- 

 ing. The operculum is, moreover, relatively larger in 5. salar 

 than in 5. Gloveri or 5. trutta of Europe, indeed than in any 

 other recorded salmonoid. The maxillary in the adult sal- 



HEAD OF SALMO GLOVERI. 



mon extends as far back as the posterior margin of the 

 eye, but in Glover's trout (/) it reaches further ; and 

 whilst it reaches only to the middle of the eye in the parr 

 and smalt of the salmon, in the same conditions of Glover's 

 salmon trout I found it extending almost to the posterior 

 margin of the orbit. 



The vomer has a double row of small teeth in the young 

 salmon, whereas there is only a single row in the smalt of 

 S. Gloveri. The number of vertebrae also differ, being fifty- 

 nine in the former and fifty-seven in the latter ; as also the 

 pyloric coeca, which from numerous instances I found to 



