2-47 



THE DESMID FLORA OF DARTMOOR. 



By G. T. Harris. 



Communicated by J. Burton. 



{Read March 27th, 1917.) 



Plates 18, 19. 



The Desmid flora of Dartmoor does not seem to have received 

 much attention if one may judge by the literature dealing with 

 it. E. Parfitt published a paper in the Transactions of the 

 Devonshire Association (1) on the Devon Freshwater Algae, in 

 which is given a list of the desmids then known to occur in the 

 county. In this list of eighty-five species only nine are definitely 

 stated to have been collected on Dartmoor, though it is probable 

 that many of the species in Mrs. Griffiths' collection were obtained 

 from Dartmoor localities. A. W. Bennett in the Journal of 

 the Royal Microscopical Society (2) published a list of the species 

 of Freshwater Algae collected by him in Hampshire and Devon- 

 shire in 1888 and 1889, the month being August in each year. 

 In this paper he gives a list of forty-six species and varieties of 

 desmids collected in the neighbourhood of Bovey Tracey and 

 Buckfastleigh, but what species were collected on Dartmoor 

 itself is not stated, merely a statement that the Dartmoor 

 gatherings were very poor "both in individuals and species." 

 Miss Joanna Town has published (3) a list of desmids collected 

 on Haytor Moor and Bovey Heathfield, but here again there 

 is no indication of the species actually collected on the moor. 

 In West's Monograph of the British Desmidiaceae (4) Dartmoor 

 habitats are specifically mentioned in only a few instances, 

 though the records for the county may possibly include Dart- 

 moor localities. 



The section of Dartmoor dealt with in the present paper is 

 the great central portion comprised between Cawsand Beacon on 

 the northern extremity of the moor, and Believer Tor on the 

 southern, with Metherall as its eastern boundary and Lydford 

 as its western. This area is roughly a square of some one 



