THE MARINE ALG^ OF GUERNSEY. 



Br Lilian Lyle, F.L.S. 



I. Introduction. 



The little island of Guernsey is well known for its rich harvests 

 of seaweed, which at stated times of the year are gathered for fuel, 

 manure, etc. Such fertility among the coarser kinds extends to 

 those of more delicate structure, for, though naturally not so profuse, 

 there is a wide range of species of considerable interest to the marine 

 botanist. 



Having spent several months of the years 1911, 1912, and 1914 

 in collecting round these coasts, my efforts were rewarded by the 

 discovery of various species, new either to Guernsey, to the Channel 

 Islands, or to Britain. It is therefore hoped that a revised list of all 

 the known species of Guernsey Marine Algie will prove of interest to 

 students. The gatherings were made between March and November 

 of the respective years, along the shore, among the rocks at low tide, 

 or from a boat by means of a dredge — some specimens were found 

 floating. 



The results of an attempt to study the growth and distribution of 

 the seaweeds of Guernsey from an ecological point of view are also 

 given. They are very inadequate and far from complete. In 1914, 

 I had intended making measurements and careful observations 

 throughout the year, but after four months' work my plans had to be 

 changed, owing to the outbreak of the War. 



My thanks are due to Dr. Rendle, at whose suggestion this 

 account was undertaken, and to Miss Lorrain Smith and Mr. Gei)p, 

 all of the Department of Botany, British Museum (Nat. Hist.), for 

 their valuable advice and suggestions ; to Mr. E. M. Holmes, for help 

 in naming Algai ; to Mr. Paulson, for naming lichens ; to Mr. and 

 Mrs. Lemesurier, of Guernsey, for their interest and assistance in the 

 matter of dredging ; and to Captain Cameron, N.Z.S.C.,for informa- 

 tion regarding winds and tides affecting the Channel Islands. I was 

 also indebted to the late Mr. Best, of Guernsey, for hints on the 

 economics of Algse. 



Previous Lists. 



The rich and varied marine vegetation of the Channel Islands has 

 attracted the attention of many botanists. Of these the late Mr. 

 Marquand is well known ; his Flora of Guernsey (1901) includes 

 236 species of seaweeds found mostly by himself, together with lists 

 of such earlier collectors as Greville and Le Lievre. In 1908 he pub- 

 lished still further additions to the Marine Algse of Guernsey, making 

 a total of 257 species for the island. A new edition of Holmes and 

 Batters's Marine Brifish AlgcB appeared in 1902, in which Mr. Mar- 

 quand's lists up to date were included. Dr. Van Heurck collected in 

 the Channel Islands, more especially in Jersey, which he worked 

 most thoroughly. His Prodrome de la Flore des Algues Marines 

 des lies Anglo-Normands (1908) contains Mr. Marquand's list for 

 Guernsey, as also does Chalon's Liste des Ahjues Marines (1905). 



In view of these exhaustive gatherings, it seemed almost hopeless 

 JouENAL OF Botany, June, 1920. [Supplement II.] h 



