34 THE MARINE ALGiE OF UUEllNSEY 



are represented mostly b}' L. digitata and SaccorJiiza polt/schides at 

 low tide, but further from the shore towards the open sea they are 

 replaced by L. CI oust out (see p. 42). 



III. The Sheltered Type. 



In deep creeks and inlets in the south, Bordeaux in the east, and 

 L'Ancresse in the north, this type of vegetation, as would be expected, 

 is extremely luxuriant and diversified, and comprises man}'- rare species. 



The ChlorophycecB are much in evidence, as are also profuse 

 growths of Porphyra, Rhodymenia palmata, Ghondrus crispus, 

 Oigartina stellata, Oracilaria confervoides, etc. Of the Fuci, — • 

 F. spiralis var. platycarpics, F. vesiculosus, and F. serratus 

 are the most noticeable species ; Ascophylliim nodosum is only 

 represented b}^ a few plants here and there. Along the sides of bays, 

 low rocks, when half buried in the sand, as at Petit Port, are often 

 covered with tufts or cushions of Bhodochorton -Jloridulum, etc. 

 Patches of soft encrusting alg.ie such ;as Codium adharenSy Petros- 

 pongium BerJceleyi, IIilde)ihrandtia onihra, and Ealfsia sp. are 

 found scattered over boulders and stones ; the rare Gigartina 

 2)istiUata, Crouania attenuata, NitophyJIum IliUice, Cladophora 

 pellucida, and Helminthocladia i)iirpurascens, may be gathered at 

 low tide, or from shady rock-pools. Dudresnaya verticiUata, 

 Bonnemaisonia asparagoides, etc., frequently drift from deep water 

 into the quiet bays, together with long fronds of Desmarestia 

 ligidata, 2). aculeata, and Ilalidrys siliquosa. Enormous plants 

 of Viva latissima are also characteristic of these localities. Lami- 

 naria saccharina is the typical plant of that genus in sheltered 

 districts, as Mr. Cotton observed at Clare Bay. 



IV. The Moderately Sheltered Type. 



The features of this type are very varied and constitute a mingling 

 of saxicolous, psammophilous, and transitional floras, together with 

 the vegetation of Zostera beds. Pelvetia is extremel}^ local— here 

 absent, there scant}^ then forming an enormous expanse of many 

 square yards, as at Port Grat, etc. Porphyra is mostly a" spring 

 growth and occurs just about high-water mark. P. leucosticta 

 appears about the same time, but at half-tide level. Enteromorphas 

 and Cladojjhoras are abundant, and so are the species of the " Fucus 

 belt," F. platycarpus and F. serratus being those most in evidence. 

 AscophyUum nodosum is present, though only in imtches here and 

 there, but not so scanty as in the previous iy])e. There is much 

 intermingling of the brown algae. A widespread growth of Chondrus 

 crispus occurs among the shallow rocks and pools, and masses of 

 Phodymenia palmata hang from platforms and rocky ledges. The 

 encrusting algae — Peyssonnelia sp. and Palfsia spp. — are very 

 prominent from half tide down to low water on small stones, they 

 alternate with sand-dwellers such as Phodochorton^ Chondria dasy- 

 phylla, Cladostephus spongiosus where there are patches of sand ; 

 while here and there Zostera beds with their various ejiiphytes occur. 



