Clare Island Survey — Marine Algae. 15 161 



At the same time it should be remembered that several large and conspicuous 

 species were found only once. 



Of southern algae, Cattithamnion tetricum may be safely stated to 

 be absent. This coarse, shaggy species is known from Minister and 

 Leinster, and from the southern counties of England. 1 Its habitat— steep 

 sides of rocks— was carefully searched on each visit, but without success. 

 There appears to be no record north of Bantry. Hufopitky* piuastroitles 

 is certainly absent, 2 and probably Pterosiphonia complanata. With regard to 

 northern species, Odonthalia dentata and Rhodomela lycopodioides 3 are wanting. 

 They are found in Ulster, but do not extend far down the west coast. 

 Monostroma fuscum was searched for in vain, probably for the same reason ; 

 it is abundant in Belfast Lough, and many parts of Clew Bay offer similar 

 ground. 



Of very rare species, Stenogramme iuterrupta, a singular plant found in 

 many parts of the world, and which occurs in the south of England, and at 

 Cork and Portaferry (Co. Down), was not found in any of the Clew Bay 

 dredgings. By some it is regarded as an alien on our shores. A special search 

 was made amongst the Fuci, but nothing approaching the curious Fucks 

 anceps Harv. and Ward, of Kilkee was seen. Spyridia filumentosa should also 

 be mentioned. This is locally abundant on the south coast of England, and 

 in AVales reaches as far north as Holyhead; yet in Ireland it is unknown- 

 A single specimen was found amongst dried material brought home from Achill 

 in July, 1909 ; but as the plant was never observed during the Survey, there 

 can be little doubt that it was an English specimen which was taken over to 

 Achill with the drying paper. 



Analysis of the Flora. 



An attempt was made, but without much success, to classify the Clare 

 Island flora after the method adopted by Borgesen and Jonsson ('05). These 

 authors recognize five groups, arctic, sub-arctic, boreal-arctic, cold-boreal, 

 warm-boreal, and have with much care classified the arctic and northernmost 

 Atlantic floras according to this scheme. But the Clare Island investigations 

 will probably tend to modify the views held in some cases ; and in assigning 

 plants to groups such as these, the personal factor cannot be eliminated. A 

 great many Irish species do not fall into any of the five divisions, owing to the 

 fact that the flora contains elements which belong to more southern regions. 

 These species it is by no means easy to classify, chiefly on account of the 



1 The Cromer record in Batters ("02), is probably incorrect. 



2 The Irish records of this plant require confirmation. 



-Adams gives a Minister record fori?, hjcopodioides ; but the case should be re-investigated. 

 R.I.A. PJtOC, VOL. XXXI, X 15 



