Adams — A Synopsis of Irish Algce^ Freslmater and Marine. 13 



marine species have been Johnson and Batters. The former's communication 

 on " Irish PhteophyceaB " before the Eoyal Irish Academy, in 1899, contained 

 a list of all known Irish species — 111 in number; while he also contributed 

 "A List of Irish Corallinacefe " to the Scientific Proceedings of the Eoyal 

 Dublin Society in the same year. 



The late Mr. Batters' chief contribution to the knowledge of Irish Algae 

 was a Eeport on the Marine Alga; of Lambay in the Iruli Naturalist for 

 1907, in which 202 species were enumerated. 



Among freshwater forms the only recent workers have been the Wests, 

 father and son. In 1892 William West published an important paper on 

 the " Freshwater Algte of West Ireland," dealing with 617 species. In 

 1902 they read conjointly before the Eoyal Irish Academy an equally 

 important communication on the "Freshwater Algae of the Korth of 

 Ireland," containing 614 species; while in 1906 they read a further paper 

 before the Academy on " The Plankton of Irish Lakes." 



Further historical references will be found in the Bibliography at the 

 end of this paper. 



SuitaMlity of the Climate. — Few countries are more suited for the growth 

 of a large algal flora than Ireland. Numerous large lakes at low levels 

 occur all over the country, and extremes of temperature do not exist. 

 There is a very extensive coast-line exhibiting a great variety of habitats 

 for the growth of marine species. Although many species still remain 

 to be discovered, a total of 2,213 species are included in this paper — 

 1,370 species being freshwater and 843 species marine. 



Provincial Distrihution. — A detailed account of the distribution of each 

 species has not been attempted. My object has rather been to give a concise 

 view of all species known to occur in Ireland ; but at the same time the 

 distribution in each of the four provinces is indicated. Where a species is 

 indicated as having been found in each province, or in three out of the four, 

 it may safely be assumed in most cases that it is generally distributed all 

 over the country, and little object would be served by giving its distribution 

 more minutely. On the other hand, if it is recorded from one province only, 

 it may be that its distribution is much more local, and further observations 

 must be made to determine this point. In a few cases the original record of 

 the species gives no locality further than that it occurred in Ireland. 



I was led to select the four pro\dnces as the chief areas of distribution by 

 the following considerations. As political divisions of the country, they are 

 in common use equally with the county divisions. Geographically they are 

 on the whole almost as natural divisions as any others into which the 

 country could be divided, and they show considerable variations of climate in 



