DESMID FLORA OF DARTMOOR. 259 



(83) Closterium Malinvernianum De Not. The single locality 

 for this species is, strictly speaking, not properly placed 

 by being included in the Dartmoor list. It was collected 

 from the perpendicular face of a dripping rock in Lydford 

 Gorge, which is situated on the extreme western fringe 

 of the moor. It is included, with Cosmarium speciosum 

 to be mentioned later, in the present list to record it 

 for the county, though as a matter of fact Lydford Gorge 

 is so nearly a part of Dartmoor (as Tavy Cleave is in the 

 same district) that any misrepresentation is not of a 

 serious nature. 

 (87) Closterium pusillum var. monoliihum Wittr. Typical G. 

 pusillum does not occur in the British Isles and the 

 varieties seem to be very rare. Gurnard's Head, Corn- 

 wall, is the only British station hitherto known for the 

 variety monoliihum. 

 (99) Tetmemorus Brebissonii var. minor De Bary. A northern 

 desmid judging by the recorded stations, but one fre- 

 quently found on Dartmoor. 



(105) Euastrum affine Ralfs, forma scrobiculata Nordst {Teste, 

 Professor G. S. West) is new to Britain (vide British 

 Desmidiaceae, vol. ii. p. 18). 



(114) Euastrum crassum var. scrobiculatum Lund. " A very 

 characteristic variety of rare occurrence " (West in 

 British Desmidiaceae). 



(120) Euastrum dubium var. Snowdoniense (Turn.) West. 

 Turner, who originally described this as a species under 

 E. Snowdoniense, seems to have been the only one to 

 record it. It is certainly present in several of the older 

 Dartmoor bogs. West has now sunk it to varietal rank 

 under E. dubium. 



(139) Euastrum validum W. and G. S. West has hitherto only 

 been recorded for the extreme north-west of Scotland. 



(142) Euastrum Webbianum Turn. The diagnosis of this species 

 is somewhat doubtful. 



(250) Cosmarium Ralfsii var. montanum Racib. is a desmid only 

 so far recorded from Carrautuohill, Co. Kerry. It is 

 not uncommon on Dartmoor. 



