Adams — A Synopsis of Irish Algm ^Freshwater and Marine. 37 



Summary of Distribution. — The number of freshwater species occurring 

 in each of the four provinces and in the whole of Ireland is shown in the 



following table : — 





M 



L 



C 



U 



Ireland 



FlagellatiB, .... 



4 







3 



3 



7 



Peiidiniese, .... 



4 



1 



5 



5 



11 



Diatoiiiaceaa, .... 



157 



204 



153 



200 



297 



Cyanophycete, 



61 



115 



57 



88 



191 



Conjugatce — 













(a) Desmidiaceae, 



302 



300 



373 



329 



542 



(b) Other Coiijngatse, 



13 



27 



6 



9 



36 



Chlorophycea;, 



94 



154 



97 



126 



275 



Rhodophycese, 



Total, . 



4 



10 



2 



6 



11 



639 



811 



696 



766 



1370 



General Remarhs on Distribution. — It is scarcely possible as yet to make 

 any broad generalisations on the distribution of Irish Algte, A noteworthy 

 feature is the presence of a very considerable number of species in Ireland 

 which are not known so far to occur in Great Britain. Equally striking is 

 the large number of species of Desmids — namely, 542 — out of a total of about 

 690 species recorded for the British Islands. West has recently called 

 attention to the striking resemblance between the algal flora of Connemara 

 and that of the north-western parts of Scotland. The following are some of 

 the most remarkable examples of distribution : — Peridinium limbatum 

 Lemm., in Co. Galway and United States ; Bimdaria Beccariana Born, 

 et Flah., in Donegal, France, and Italy ; Tolypotlirix arenophila, W. & G. S. 

 West, in Down and West Africa ; HyiJlieothrix delicatissima Forti, in Down, 

 West Africa, and Ceylon; CmlosphcBriiim minutissimum Lemm., in Lough JSTeagh 

 and Germany ; Gonatozygon monotcenium var. pilosellum Nordst., in Dublin 

 Mountains and Brazil ; Cylindrocystis minutissima Turn., in Lough Neagh, 

 India, and Ceylon ; Sjpirotcenia trabeculata A. Br., in Donegal and Saxony ; 

 Pleurotcenium tridentulum var. capitatum West, in County Galway and 

 United States of America ; Cosmarium goniodes W. and G. S. West, in 

 Donegal, south of England, and Madagascar; Cosmocladium suhramosum 

 Schmidle, in Donegal and Germany; Desmidium BsetcdostrejJtonema W. & G. S. 

 West, in Co. Galway and Ceylon ; Staiirastrum sinense Liitkem., in Donegal 

 and mountains of Central China ; Staurastrum sulgracillimum W. & G. S. West, 

 in Donegal and United States; Dictyocystis Hitchcochii Lagerh., in Donegal 

 and United States ; (Edogonium Hirnii Gutw., in Donegal and Austria. 



