450 Mr. McClelland^ Catalogue 



would appear that the differences here noticed in the Char 

 are chiefly induced by locality, but this, in itself, is rather an 

 effect than a cause. The cause is, I conceive, based on geo- 

 logical influences, as the "formation" in which the lake in- 

 habited by this fish is situated, and whether there be a pre- 

 valence of rock, gravel, sand, or peat — if fed by springs or a 

 goodly river, and if the latter the formation through which 

 it flows — the depth of water, &c. According to these features, 

 the quality of the water, and the minute animals constituting 

 the food of the Char will vary, and the latter not only in the 

 quantity produced, but in species. According to its food the 

 external appearance of this fish is influenced, as well as the 

 flavour and colour of its flesh. No proper comparison, again, 

 can in any respect be made between the Char of different lo- 

 calities unless the examples be in similar condition, and 

 which, as before mentioned, they sometimes are not in adja- 

 cent lakes at the same period of the year. A great deal might 

 be said on the manifold influences affecting this species, 

 but it is for my friends, the authors of the two great works 

 now in progress — M. Agassiz in his s Freshwater Fishes of 

 Central Europe/ and Sir W. Jardine in his ' Scottish Sal- 

 monidae' — to descant upon them. 



When my attention was first given to this subject, I in- 

 tended to enter fully into the history of the Char as a British 

 species. This would now be superfluous, and I content my- 

 self with contributing the rough notes made upon the sub- 

 ject, as ere long we shall doubtless have before us, in the 

 works just mentioned, a most ample history of the Salmo 

 Urnbla. 



LII. — A List of Mammalia and Birds collected in Assam 

 by John McClelland, Esq., Assistant Surgeon in the service 

 of the East India Company, Bengal Establishment : revised 

 by T. Horsfield, M.D., V.P.L.S., &c*. 



[Concluded from p. 374.] 



Order II. INSESSORES, Vigors. 



Tribus Fissirostres, Cuv. 



Fam. Meropid^e. 



Genus Nyctiornis, Swains. Zool. Illust. II. PI. 56. 



9. Nyctiornis Athertonii. 



"Toes much longer than the tarsi ; outer ones united to the last 



* Communicated by Dr. Horsfield to the Zoological Society of London, 

 Oct. 22, 1839, and extracted from the Proceedings of the Society. 



