2 THE MARINE ALGJ3 OF UUEHNSEY 



that further search Avould yield any additional species. When it is 

 remembered, however, that " some species are very uncertain in their 

 appearance, occurring in abundance, perhaps, during one season and 

 then disaj^pearing for years," and when it is also borne in mind that 

 currents and other agents frequently bring new species or their 

 spores from long distances to establish themselves and even spread 

 along our coasts — as, for example, Colpomenia sinuosa, Bonnemaisonia 

 asjmragoides^. liamifera, etc., — one need never despair of making new 

 discoveries. This was, indeed, my fortune, for I was able to find 

 46 species, 22 varieties, and 4 forms new to the Channel Islands ; 

 46 species, 6 varieties, new to Guernsey ; 3 species and 2 forms new 

 to Britain ; 1 species and 1 form new to science. 



The total number of alg^e for Guernsey, including those already 

 listed by other workers is now SoO species, 78 varieties and forms. 



Mr. Marquand throws some doubt on the existence of certain 

 algae mentioned in the lists of Miss Le Lievre and Dr. Greville, or 

 on their correct determination, as, after years of diligent search, he 

 failed to find them. These are : — 



Gystoselra harhata^ Fiicus ceranoides, Sporochmis pedunculah^s, 

 Cutleria multifida, Sphacelaria Serfularia, Ecfocarjms Mertensii., 

 Daysa venusta, Nitophyllum Gmelini, Kallymenia Duhyi, Ceramiuni 

 ■flabelligerumy Callithamnion arhuscula, Callifhamnion roseum^ and 

 Cladopkora repens : also Desmarestia viridis, Dicfyosiphon fcenicu- 

 laceus, and Bytlphloea pinasfroides of Greville's list. 



Gystoselra harhata is excluded from the British Flora by Batters 

 as a waif. Fucus ceranoides is usually found in the estuaries of 

 rivers. The absence of an}* large body of fresh ^vater in Guernsey 

 would tend to preclude the idea of its existence on these shores, 

 Gutleria nmltifida, Desmarestia viridis, SporocJuius pediniculatus, 

 Tllopteris Mertensii are all mentioned in Batters's Marine Algce as 

 growing in Guernse}^, but they have not been found recently. Calli- 

 thamnion arhuscula is an inhabitant of northern regions, and is 

 replaced by G. spo7igiosuni in the south: with the exception of 

 localities where northern and southern floristic elements mingle — as, 

 for instance, on the west coast of Ireland, — the two species never grow 

 too-ether. It is therefore hardly likely that G. arhuscula was col- 

 lected in Guernsey, although G. spongiosum grows abundantly. 

 Nitopliyllum Gmelini and Gladophora repens are indicated by Mar- 

 quand in his lists for Alderney, but they have not been found in 

 Guernsey. 



As regards the other missing species, Mr. Marquand suggests 

 that they may have disappeared for a time to reapj^ear later on. The 

 fact that I was able to find five of them — Scliizymenia Diihyi^ 

 Geramiumjiahelligerum, and Polysiphonia elongata in 1911 ; Halo- 

 pitliys pinastroides in 1911, 1912, 1914; Dictyosiplwn foenicu- 

 laceus in 1912; and S2)liacelaria Sertularia in 1914 — is in favour of 

 his view. In no two years does it seem possible to find all the same 



I was able to find three of Mr. Marquand's four additions to the 

 British Flora, viz : — Strehlonema Zanardinii, Liehmannia Leveillei, 

 auiX LitJiothamnion expansiim: but, though I searched diligently in 



