15 86 Proceedings of the Royal Iri.sk Academy. 



sequence and depth of the bands on Loamy or peaty banks about 4 feet high 

 is as under : — 



Rivularia Biasolettiana (rarely presenl , . . 1 inch, 



l'hoeococcns adnatus (not always present), . 2 inches. 



Rivularia nitida, 9 ins.-l foot. 



Rhizoclonium and Enteromorpha, . . . 2 feet. 



Vaucheria coronata and E. intestinalis var., . 1 foot. 



In narrow creaks (which possess little light), Vaucheria coronata clothes 

 the entire Burface of the banks, growing very luxuriantly up to extreme high- 

 water level. Tt forms here a loose furry growth (due to copious branching) 

 instead- of the short velvet pile found in open places. Where the banks are 

 flat the growth spreads out horizontally, and (he clear zonation is lost. 

 Phoeococcus and Rivularia nitida usually disappear (cf. Bellacragher Bay, 

 p. 89), Ehizoclonium, Percursaria, and Enteromorpha taking their place, and 

 running in amongst Statice maritima, Glaux maritima, and Glyceria maritima, 

 so that the whole forms a miniature salt-marsh. 



With regard to seasonal development and other details, R. nitida, 

 Rhizoclonium, Enteromorpha, Vaucheria coronata are found at all seasons. 

 R. Biasolettiana is perhaps mostty a winter and spring species, it being noted in 

 quantity in May only. Phoeococcus forms, on the loamy banks of the 

 Imnowen, a narrow band (cf. Achill, p. S3), and is in places entirely absent. 

 It reaches its maximum development in late summer and autumn, and occurs 

 above the average high-water mark. R. nitida is likewise most conspicuous 

 in autumn ; in favoured spots the greenish-black band, a foot deep, stretches 

 for many yards; in others it is intermittent, due possibly to the crumbling 

 away of the soil. The Ehi/oelonium-Enteromorpha association is practically 

 uninterrupted, ami is more luxuriant in spring, forming a bright apple-green 

 belt ; in summer it becomes bleached, and the Enteromorpha constituents are 

 dominant. Monostroma sp. (= M. crepidinum ? see p. 107), noted in spring, 

 summer, and autumn, is scattered irregularly throughout this growth; but it 

 is never copious, and is apt to be overlooked. The lower part of the 

 association, which consists of narrow varieties of Enter omorpim intestinalis, 

 merges into the Vaucheria coronata zone*. The last-named often stretches a 

 long distance as a pure growth, forming a dark-green, very short, velvet pile. 

 It fruits abundantly, no difficulty being found during any visit in obtaining 

 the characteristic oogonia. If stones exist, F. ceranoides may occur near low- 

 water level ; but its growth is poor. 



Fhit Sloping Banks. — Close to the mouth, the vertical banks give place 

 first lo linn mud and then to stony banks, with more or less sand. The 



