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Memorandum regarding Salmo Orientalis, or Bamean Trout. 

 By Mr. Griffith. 



Plate I is a reduced figure from an original drawing 

 of Salmo Oriental, the species is described p. 585 of the se- 

 cond volume of this work, as inhabiting the tributaries of 

 the Oxus, on the northern declivities of Hindoo Koosh. 

 There is no fact in Natural History so characteristic of the 

 peculiar laws to which the distribution of species is subject, 

 as the occurrence of Salmons on the northern declivities of 

 the Hindoo Koosh, contrasted with the equally well establish- 

 ed fact of their absence, not merely on the southern decli- 

 vities of the same chain, but also throughout the rivers of 

 AfFganisthan and India. Considered by itself, or merely with 

 regard to temperature, latitude, longitude, and elevation, it 

 would be quite inexplicable; but on the other hand, when 

 viewed in relation to the well-known habits of the Salmons, 

 it is only what might be expected. The Salmons are known 

 to belong to the seas of temperate climates, and to enter 

 the mouths of rivers during spring, and penetrating to their 

 extreme tributaries, there deposit their spawn in the gravel, 

 beyond the reach of various injuries to which it would be 

 subject, as well as the young fry, in less remote situations. 

 However suitable the Himalyan and other mountain streams 

 south of the boundary just noticed might be in point of 

 temperature, and other circumstances adapted to the deve- 

 lopment of the young Salmon, yet the tropical seas into which 

 these waters fall would be fatal to them, so that the absence 

 of Salmon may be easily accounted for in all countries, the 

 rivers of which have no communication with the seas of 

 the temperate climates. The sea is essential to the Salmon, 

 indeed it is their natural abode, as they leave it only for 

 the purpose of spawning. It is evident, therefore, that the 

 Salmon must ascend the Oxus from the sea of Aral, a dis- 



