Clare Island Survey -Marine Algae, 15 89 



Encrusting Algae. — IMhothamnium polymorphism belt well developed, 



usually with Corallina officinalis. 

 Pebble-attached association. — Extensive and well developed, but poor in 



species. Examined by wading at extreme low-water. 

 Zosii ra. — Local. 



Special features. — Two societies not referred to elsewhere are very 

 prominent in the littoral region. (1) Eivularia nitida, the species of vertical 

 peat-banks (p. 82), occurs as a broad horizontal band. It is noticeable 

 throughout summer, but in October forms a black band along the whole shore. 

 (2) Cladophora rupestris, as narrow strips or effused patches, is also very 

 abundant. indicating the presence of fresh water. It is remarkable that 

 Enteromorpha, which usually serves this purpose, is, except as a short 

 growth near high-water line, almost absent. Associations of Porphyra 

 and Ehodochorton, which might have been expected, were completely 

 absent. 



A general coating of the diatom Goeconeis Scutellum is especially 

 characteristic of the vegetation of this bay. Species of Cladophora, Ectocarpus, 

 Polysiphonia, etc., are in spring so completely covered as to be utterly 

 unrecognizable. The plants appear quite black owing to a ring of brown 

 substance round the valves of the diatom. The ring is apparently secreted 

 from the peaty water by Cocconeis. Mr. W. AVest, who kindly identified 

 the diatom, tells me such a copious deposit is unfamiliar to him. 



Fresh-water streams. — See p. 87. 



With regard to the flora, the lists kept show that a Aery large number of 

 species occur in the bay, but in small quantity only. Many species were only 

 found once, but, on account of the poorness of the tide, the low-littoral flora 

 is compressed into a very small space. The dominant associations — Fucaceae. 

 Laminaria, Zostera, and pebble-attached — practically cover the ground, and 

 there are no pools. This type of vegetation is probably not peculiar to Bella- 

 cragher Bay, as from cursory observations elsewhere (Killary, Eoundstone, 

 also in Scotland) it appears to be frequent in brackish bays of like nature. 

 In summer Cyanophyceae are abundant, especially Lt/nr/oi/a majuscula, Calo- 

 tlirix aeruginea, C confcrvicula, and Anabaena torulosa. Stictyosiphon subarti- 

 eulata, Dictyosiphon foeniculoxeus, Striaria attenuata, and Chylodadia 

 kaliformis are dominant on pebbles in spring; whilst in summer Cladophora 

 Rudolphiana, EnieromorpTi clathrata var., and Spermatochnus occur in extra- 

 ordinary profusion. Of species apparently absent, the following may be 

 noted: — Mesogloia vermiculata, Nitophyllwm punctatum, GriffUhsia corallina, 

 67. setacca, and Monospora pedicellata. 



R.I.A. PROC, VOL. XXXI. M 15 



