Clare Island Survey — Marine Algae. 15 171 



austral and southern elements dealt with above ; but a further word may 

 be said as to the comparison between the east and west coasts of Ireland. 

 As far as can be seen from records, and from a study of herbarium material, 

 the east-coast flora is characterized not so much by a poverty of species 

 as by a smaller proportion of the austral element, and by a lack of the 

 special luxuriance characteristic of the west. It appears useless at present 

 to attempt to pronounce an opinion as to the origin of the species on 

 either coast. The fact that Colpomenia sinuosa can suddenly appear in 

 Brittany and Cornwall, and in the course of a few years be completely 

 naturalized over a very large area on both sides of the English Channel, 

 proves how quickly changes may take place, and how easily we may err in 

 discussing the age and history of a flora. 



There remain two isolated species to be noted. Bonncmaisonia hamifera, 

 a fairly conspicuous and unmistakable alga, is elsewhere in Europe known 

 only from a few stations on either side of the English Channel. It occurs 

 in the North Pacific (Japan and California), and has usually been regarded as 

 an alien in this country. The plant is dealt with on p. 136; but nothing can be 

 stated as to origin in Clare Island, owing to our complete ignorance of its 

 range in Ireland. Codium mucronatum var. atlanticum is even more note- 

 worthy. So closely allied to the New Zealand form of the species as to be 

 almost inseparable from it, and yet unknown in the northern hemisphere 

 except in the British Isles, its distribution is certainly remarkable. As far as 

 is known, it does not occur in England, but has existed in Scotland for at 

 least seventy years, and in Ireland for upwards of a hundred. Its precise 

 range has not yet been ascertained. Until each species of our flora is 

 recognized, and until its range is accurately determined, plenty of work 

 remains for the systematic algologist. Common species need not be despised. 

 On Clare Island some of the most abundant and conspicuous algae have 

 proved the most interesting ; and yet, owing to lack of data concerning their 

 distribution, we are hampered in drawing theoretical conclusions. 



V.— BIBLIOGRAPHY. 



Adams, J. ('08). A Synopsis of the Irish Algae. Proc. Roy. Irish Acad., xxvii B, 

 No. 2, p. 11. 

 ('10). A list of Synonyms of Irish Algae with additional records and obser- 

 vations. Proc. Boy. Irish Acad., xxviii B, No. 5, p. 167. 

 ('12). A census of Irish Cryptogams. Irish Nat., xx, p. 87. 



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