1908 Adams. — Irish Biological Sub-provinces. 151 



18. Praegkr, R. Lr,.— On the Botanical vSubdivisiou of Irelaud. Ir. 



Nat. vol. v., 1896. 

 19. Irish Topographical Botany. Proc. Roy. Ir. Acud. (3rd Ser.), 



vol vii., 1901. 

 20. SCHARP'F, R. P\ — The Irish Land and P'reshwater Mollusca. Irish 



Nat , vol. i., 1892. 

 2T. vSteIvFOX, a. W. — Some Notes on the Land and Freshwater Mcllusca 



of Galway and District. /;-. Nat., 1907. 



22. Stephens, Miss J. — A List of Irish Ccelenterata, including the 



Ctenophora, Proc. Roy. Ir. Acad., vol. xxv., 1905. 



23. Wright, E. P. — Notes on the Irish Actinidte. Nat, Hist. Review., 



vol. vi., 1859. 



Royal College of Science, Dublin. 



THE EXTINCTION OF CRYPTOGAMIC PLANTS IN 



IRELAND. 



BY A. R. HORWOOU. 



At the Leicester meeting of the British Association the 

 author described certain changes in the cryptogamic flora of 

 Charnwood Forest, Leicestershire, chiefl}' owing to the effect 

 of smoke. The present communication deals with the causes, 

 affecting cr3'ptogams in Ireland. Whilst it forms part of an 

 interim report on the extinction or diminution of cr3^ptogams 

 generally throughout the British Isles, it is hoped that the 

 attention here drawn to the matter in a preliminar}^ wa}' will 

 have the effect of eliciting further facts from those areas in 

 Ireland from which reports are forthcoming, as well as from 

 those districts from which at present no information has been 

 obtained. 



Causes. — From a stud}- of reports received from all parls 

 of the British Isles, and from personal observation, it appears 

 that extinction or diminution of cryptogams is due principally 

 to the following causes : — 



A. Climate. 



(a.) Changes in temperature. 

 ■^(/^) „ humidity or dryness (rainfall or 



drought). 

 (c.) „ pressure of atmosphere. 



(d.) „ movements of atmosphere. 



