Clare Island Survey — Marine Afr/ae. 15 103 



Oscillaria sancta Kiitz. 



A fresh- water species, common in Britain ; but with the exception of 

 .specimens sent out by Holmes ("Algae Rariores," No. 268) it has not been 

 recorded for our islands from a marine habitat. 



Portlea, October, 1910 ; May, 1911 ; on various algae at mouth of cave. 



0. limosa Ag. 



As in the case of many Cyanophyceae, 0. limosa, though usually a fresh- 

 water species, should certainly be included in a list of marine algae. It was 

 found intermixed with other brackish species on piles at the side of a stream 

 at Mulranny (Aug., 1911). 



In addition to the above record, a cyanophyceous growth on the sand, both 

 in Achill Sound and at Mulranny, appears to be referable to this species. At 

 Achill the growth occurred between the Fucus plants in the " farms " 

 in the middle of the Sound ; and at Mulranny it was found amongst 

 Rhizoclonium and Yaucheria on the upper part of the tidal region. The 

 filaments are straight, non-attenuated, non-capitate, bright blue-green in 

 colour, and measure 10-16 n in diameter. In some cases a distinct, somewhat 

 mucilaginous sheath is present, a peculiarity which has been noted previously 

 in 0. limosa, and which led to a distinct species, Li/ngbya obscuiu var. aestivalis, 

 being described by Hilse. The only point in which the specimens differed 

 from the normal fresh- water 0. limosa was in the filaments being at times 

 slightly torulose. 



Phormidium persicimim Gom. 



This very distinct species, which is new to the British flora, was described 

 by Reinke in 1889, and has since been recorded from various localities in 

 Europe and America. The rose colour, coupled with the exceedingly fine 

 filaments (1'5-2/a) and long cells (2-7 fi), mark it sharply off from other 

 marine species. The previous record of this plant as British (Journ. 

 Bot., xxxiv, p. 7) was an error, the plant found being Phormidium Ectocarpi 

 Gom. (Batters, '00, p. 369). 



Clare Island, October, 1910, forming a dense rose-coloured coating on 

 Godium tomentosum in a rock-pool. 



P. subuliforme Gom. 



The plant referred to this species was found with Calothrix scopv.lorum on 

 rocks near high- water line. First described by Grunow from St. Paul 

 (Pacific), it has since been recorded from Nebraska and Iceland (Journ. 

 Bot., xl, p. 245). Though not previously noted as marine, it agrees so well 



