The Scottish Naturalist. 



199 



THE DESMIDS OF THE ALFOED DISTEIOT- 



By John Roy, LL.D. 



(All measurements in subjoined list are in micromillimetres.) 



THE following list has been compiled almost wholly from 

 material furnished by Mrs. Farquharson, F.R.MS., of 

 Haughton, an enthusiastic and most successful collector. 



It will be observed that there are 184 species and 6 varieties 

 enumerated in it. Of these, some are new, and others of extreme 

 rarity. This number exceeds that given by Ralfs for the whole of 

 Britain, and is three times as great as that given in Dickie's 

 " Botanist's Guide " as occurring in the counties of Kincardine, 

 Aberdeen, and Banff. 



The alphabetical arrangement of genera, and of species in each 

 genus, being the most convenient for a list, has been followed. 



In submitting this list to the Alford meeting of the Union, the 

 Compiler trusts that it may stimulate some in other parts of 

 the district embraced by the Union, to imitate Mrs. Farquharson's 

 excellent example, and to forward gatherings to him, to 

 33 Belvidere Street, Aberdeen. 



arthrodesmus (Ehr.) Archer. 



1. Bifidus Breb. 



Little Don, Haughton ; Ditch, Meikle Moss, Alford. 



2. Convergens Ehr. 



Little Don ; Tonley. 



3. Incus (Breb.) Hass. 



Little Don, and Pond, Haughton ; Whiteley Marsh ; with 

 zygospores, near Whitehouse, and at Tonley. 



4. Octocornis Ehr. 



Correnie ; Tillyfour ; Little Don ; Tonley. 



CLOSTERIUM, NitZSCh. 



1. Acerosum, Schrank. vars. a. and b. 



Little Don \ Keig. 



2. Acutum J Breb. 



Correnie ; Tough ; Pond, Haughton, and Scott's Mill, 

 Tonley. 



3. Angustatum, Kg. 



Towie ; Tonley. 



