£"74- 



Clare Island Survey. 



15 



MARINE ALGAE. 



By A. D. COTTON. 

 Plates I.-XL 



Read Jine 24 and Sovembee 11. Published November 27, 1912. 



CONTENTS. 



I. 



Prefacf. .... 



Introduction, 



1. Definition of the Area, 



2. Previous work in the Area, 



3. Field-work and Assistance, 

 The External Conditions of the 



Area 



1. Climatic Conditions, 



2. Physical Nature of the Coast 



and Conditions of Exposure, 

 II. The Algal Vegetation, . 



1 . Historical Resume, . 



2. Areas and Units of Vegetation, 



3. The Vegetation, 



i. The Rocky-shore Formation 



(A) Exposed Coasts, 



(B) Sheltered Coasts, 



ii. The Sand and Sandy-mud 

 Formation, 



PAGE 



1 

 2 

 2 

 2 

 4 



6 

 6 



9 

 12 



12 

 14 

 17 

 17 

 19 

 50 



61 





] 

 iii. The Salt-marsh Formation, . 



•AGE 



78 





iv. The Vegetation of River- 







mouths, .... 



S3 





v. The Vegetation of Brackish 







Bays, .... 



88 



III. 



The Algal Flora, .... 



90 





1. The Systematic List, 



90 





2. Notes on the List, . . , 



102 





3. Economic Species, 



151 





4. The Flora of The Bills, . 



155 



IV. 



The Character and Composition 







of the Flora, 



156 





1. Notes on Novelties and Additions, 



156 





2. The Character of the Flora, 



160 





3. Comparison with other Areas, . 



166 





4. Origin of the Flora, . 



168 



V 



Bibliography, .... 



171 



PREFACE. 



The natural history Survey of Clare Island and . the adjoining mainland 

 provided an opportunity of investigating one of the most interesting 

 algological regions in the British Isles. Since the first decade of the last 

 century, when Miss Hutchins collected in Bantry Bay, and more especially 

 since the days when Harvey published his famous " Phycologia Britanniea," 

 the west of Ireland has always possessed a great attraction for the marine 

 botanist. But although various collections and many gatherings of new and 

 rare species have been dealt with, no systematic investigation of that area 

 has been undertaken, nor has any list or general account of the algal flora been 

 published. The selection of Clare Island as a centre for a detailed survey was 

 therefore particularly satisfactory from an algological standpoint. Results 

 for the systematist and student of plant-distribution were certain, and the 

 R.I. A, pp.oc, vol. xxxi, A 13 



