[ 441 ] 



XXVI. 



IRISH PH^OPHYCEJE (REPORT OF THE FAUNA AND 

 FLORA COMMITTEE). By THOMAS JOHNSON, D.Sc, 

 F.L.S., Professor of Botany, Royal College of Science, 

 Dublin, and HENRY HANNA, M. A., B. Sc. ; assisted by 

 MISS R. HENSMAN and MISS M. C. KNOWLES. 



[Read May 8, 1899.] 



The number of species of seaweeds recorded for Great Britain and 

 Ireland is some 700, of which some 200 are Phaeophycese, or brown 

 seaweeds. In 1890, Holmes and Batters, published a Revised List 

 of the British Marine Algae in the "Annals of Botany," the number 

 of British species there recorded being about 540. Of these the Irish 

 species numbered 235, 73 being Phseophycese, The object of this 

 paper is to record some 40 additions made since the year 1891, in 

 part in connexion with the work of the Fauna and Flora Committee. 

 The paper contains accounts of the examination of collections made at 

 many different points on the Irish coast, partly by shore-collecting, 

 partly by dredging, from time to time, since the year 1891. The 

 least known parts of the Irish coast are the extreme north and the 

 coasts of counties Wicklow and Wexford. 



It has been well said that many of the most important biological 

 problems are illustrated by, and may find their solution in a study of, 

 the low group of Algae. Thus Farmer has recently described indirect 

 nuclear division (karyokinesis) in the Fucaceae — the highest group of 

 brown seaweeds. The Phaeophyceae show a complete gradation from 

 simple conjugation to fertilization in reproduction, and Williams has 

 recently described, for the first time, the mode of reproduction in the 

 common Dictyota, &c., of the Dictyotaceae. 



There is no doubt that tliere is still a wide field of investigation as 

 to the modes of reproduction of the different members of the Phaeo- 

 phyceae. In many species the reproductive organs are still either 

 unknown or incompletely known. In relatively very few has here 

 anything like a complete life-history of a species been made out. We 



E.I. A. PltOC, SEE. III. VOL. V. 2 1 



