[206]

19

July 56

With respect to F. W. Fish I can find no cases of Fish same species in very distant countries except anadromous species & these wander far, as Salmon (Sir J. Richardson letter) occasionally seen in Baltic.

The F. W. & salt Percidæ are very like. All Fish seem to have great capacity for mutual conversion in to F. W & saline. Coregonis washed down by floods [insertion:] Richardson [illeg] & yet lives in sea.

Hardly any group purely F. W. Even Cyprinidæ not all F. W.-

Pike strongest case identical in Europe & N. America & not W. of Rocky Mountains but is found in E. Siberia

[insertion:] Cuvier & Valenciennes Hist. Nat de Poissons v. 18. p. 219

Yet these inhabits somewhat brackish water of Baltic (do p. 220) Probably found more continuous by Behring Sts. [insertion:] & in Scotland in Lakes opening into Eastern seas.  Then take Agassiz case in rivers in same continent. As far as representative species are concerned

[207]

groups generally different, on different continents except N. America & Europe & here [illeg] warmer land to N. perhaps explains.

I thought L. Jenyns case of Meritas, two close species common to T. del Fuego & N. Zealand strongest case, but I now find Cuvier & Valenciennes. Hist. Nat. des Poissons vol 18 1846.

p 264 that this is a Galaxias & that one of the very species has been been f. at Falklands in sea.

Nutria in F. W & marine islds.