1857.] • 37 



IRISH MOSSES. 



Observations on the Mosses of Ireland, with a Supplementary 

 List of Species not contained in the 'Flora Hibernica/ together 

 with their Habitats. By D. Moore, Esq., M.R.I. A., etc. etc. 



Those who have paid much attention to the geographical dis- 

 tribution of plants in this country must have observed that the 

 species and individuals, both Phsenogamic and Cryptogamic, or, 

 in other words, vascular and cellular plants, decrease in number 

 progressively from the east side of the island to the west. For 

 instance, a greater number of species are generally found in the 

 counties of Antrim, on the north-east, and Dublin, on the east 

 side, than there are in Sligo, on the north-west, and Galway, on 

 the west side. The cause of this discrepancy is hardly reconci- 

 lable to differences in their geological formations, which no doubt 

 aflFect the growth of plants very materially; neither are the 

 causes assignable to elevation and undulation of the surface, both 

 being pretty much the same in the counties I have instanced ; 

 I would rather therefore consider them to be more of a meteoro- 

 logical nature ; the west coast being so sensibly affected by the 

 Gulf stream — an equable and moderately high temperature, ac- 

 companied with a more than ordinary degree of moisture, are 

 nearly constant throughout the season — circumstances which do 

 not prevail to the same degree in other parts of the island. 

 Accordingly, among the plants in these localities large quantities 

 of a few rare species grow, which are not found elscAvhere in the 

 United Kingdom : as examples, I may instance the two Heaths, 

 Erica mediterranea, var. hibernica, and E. Mackaiana, along 

 with several Saxifrages; and, as Cryptogamic species, the well- 

 known KiUarney Fern Trichomanes radicans, and Jungermannia 

 Woodsii. 



Some species of Mosses are very local, and confined to certain 

 districts, while others are only known to grow on particular kinds 

 of rocks. Among the latter is one of our rarest and minutest 

 species, namely Weissia pusilla, which has only, I believe, been 

 observed to grow on limestone. It occurs in considerable abun- 

 dance in several places near Belfast, but I never saw it elsewhere 

 in Ireland. Again, with respect to those that are local, I never 

 found the pretty little Moss Glyphomitrion Daviesii, excepting 



