i8o ANNALS OF SCOTTISH NATURAL HISTORY 



From these sources, and from a comparison with the 

 plants still found at distances not exceeding a few miles from 

 Aberdeen under conditions similar to those that prevailed 

 formerly within its present limits, it is possible to realise in 

 some degree the changes that the flora has undergone since 

 1750. Before that date the destruction of the native woods 

 seems to have been almost if not quite complete, and with 

 them must have gone most of the plants that prefer their 

 protection. Among the influences most destructive in their 

 effects on the native flora were the changes due to the 

 drainage of the wet hollows, in part occupied by peat-mosses 

 and in part by marshes not on peat ; and numerous species 

 have become extinct in this way. Others have disappeared 

 in consequence of the alterations at the mouths of the Dee 

 and Don, and on the Links between the rivers. 



(To be continued.} 



NOTES ON THE GENUS POTAMOGETON OF 

 THE LONDON CATALOGUE. ED. 10. 



By ARTHUR BENNETT. 



IN the "Journal of Botany " (1907), pp. 172-76, I remarked 

 on some forms of the genus new to Britain. In this note I 

 run through the names and add, or reject, as later know- 

 ledge suggests. 



1. P. NATANS, Z., var. TERRESTRE. Gray, "Nat. Arr. Brit. PI." 



(1821), p. 33. Woking, Surrey, A. Bennett. 



2. P. POLYGONIFOLIUS, Pourr., var. AMPHIBIUS. Fries, "Nov. 



Fl. Suec." (1828), p. 30 ( = ericetorum, Syme). 



var. SPHAGNOPHILA. Neuman, " Bot. Not." (1896), 

 91. Moidart, Argyll, Symers Macvicar, sp, 



var. CORDIFOLIA. Asch. et Graeb., "Syn. Fl. Mitt. 

 Europ." (1897), p. 306. 



A large cordate-leaved form, not uncommon. 



P. POLYGONIFOLIUS x NATANS ( = P. Gess?iacensis). Fischer, 

 in " Ber. Bayr. Bot. Ges.," xi. (1907), p. 20. Rudha 

 Gheadha, Isle of Colonsay, Argyll, M. M'Neal, sp. 



