In this communication the author first gives an account of the occurrence of the Vendace (a fish hither to supposed to be confined to the lochs of Lochmaben in Dumfries-shire) in two of the lakes of Cumberland, viz., Derwentwater and Bassenthwaite Lake, in each of which it seems to be pretty abundant, and to have been long known to the boatmen; secondly, he offers some speculative suggestions as to the diffusion of species in the instance of this fish, giving the preference to that presuming that its transfer might have been accidentally effected by the impregnated ova being conveyed by aquatic animals