42 THE MARINE ALO.T: OF UUERNSET 



Lamuiaria Zone. 



Owing to the imi^ossibilitj of obtaining a boat except along the 

 east coat, the study of the Laminarias was limited to observations at 

 spring tides or of the weed thrown up on the shore. The enormous 

 quantities of the latter heaped up in banks along the west coast, 

 espscially in autumn, lead one to conclude that there must be an 

 extremely wide Zone of the genus in this district. Further round the 

 island the debris decreases considerably, so possibly the Zone is 

 narrower along the other shores. The influences of climate on a 

 genus, resulting as pointed out by Cotton in changes of species 

 according to changing conditions, are clearly illustrated by the 

 Laminarias of Guernse}'. 



In the exposed type of flora, round Pleinmont, the Laminaria 

 Zone consists in its upper portion of L. digitafa and Saccorhiza 

 polijscliidesy whilst extremely low tides reveal the presence of 

 L. Cloiistoni. Those plants nearest the shore are short, further out 

 they increase to 3 or 4 ft. in length. The rough stipes of L, Cloiistoni 

 bear a plentiful crop of epiphytes, among which may be mentioned 

 Ectocarpus siliquosus^ Rhodymenia palmafa, Ptilothamnion pluma, 

 Delesseria sinuosa,D. alata, Fhyllophora jyalniettoides, Polysiplionla 

 iirceolata var. patens, Lomentaria articulata. A plentiful growth 

 of Callitliamnion tetragonum occurs on the blades of L. difjitata. 



The epiphytes on the stipes of SaccJiorhiza polyscliides are Ecto- 

 carpus Kinchsice, E. arctus,E. Crouani, 3Iyrionema reptans, ?i thick 

 felt of Chantransia Lorrain-SmithicB. 



Curiously enough some large and fine species of L. saccliarina 

 were seen in tliis district usually connected with shelter, they had 

 possibly grown in deep fissures. 



In the Flora of Type II., the Semi-exposed, along the west coast, 

 there is first a small amount of X. saccliarina mixed with Chorda 

 Jilnm and JJlva latissima ; these are succeeded by L. diyitata mixed 

 with Sacchorhiza poJyschides, whilst still further out L. Cloiistoni 

 becomes the dominant species. As shelter increases L. saccliarina, 

 the characteristic plant for protected areas, gains ground and finally 

 displaces other species. It is almost the only Laminaria found in 

 secluded creeks and quiet bays. 



L. Cloiistoni was not observed along the east and south coasts : it 

 may have been overlooked. As the open sea is the more suitable 

 habitat for this plant, viz. along the nortli and west coasts of 

 Gruernsey facing the English Channel, it is possible that the narrower 

 and more confined waters between the Channel Islands and the French 

 coast are less favourable to its growth. 



{d) Pool Vegetation. 



Shore pools above high-v>'ater mark are more or less brackish, as 

 they collect rain water and are rarely flushed by the sea. Most of 

 them are shallow and fully exposed to the sun's rays, and therefore 

 during summer become quite warm. They contain few algte ; 

 Enteromorplia intestinalis is the most frequent. In pools lower down, 



