684 Proceedings of the Royal Irish Academy. 



OpMoglossum vidqatum (Liun.) — RemarkalDly abundant on the northern 

 slope of Pilot's Hill. 



Eqxtisetace^, 



Eqimetum arvense (Linn.) — Ditch-banks east of the castle. 



It has occurred to me that a comparison between the floras of an 

 island upon the east and one upon the west coast of Ireland would be 

 of interest. Eeliable means for such a comparison are available in 

 Mr. llore's " Eeport on the Flora of Inish-Bofin, Co. Galway,"^ an 

 island which lies almost exactly in the same latitude upon the west of 

 Ireland as Lambay does upon the east. These islands are both devoid 

 of limestone, and there is no geological dissimilarity which would 

 entail any important difference in their floras. Their coast lines are 

 alike in character, and their difference in elevation is trifling, Lambay 

 being about a hundred feet higher than Inish-Bofin. Inish-Bofin has, 

 however, about four times the area of Lambay, and the western island 

 has also a great superiority in possessing " four small lakes and a few 

 pools with a considerable extent of moist and boggy ground producing 

 a fair proportion of water plants, sedges, rushes," &c. Lambay has, as 

 we have seen, neither lake nor turf -bog, and very little ground suitable 

 for any of the marsh or aquatic species. The contrast which I pro- 

 pose to di'aw has for its object the illustration of the differences arising 

 from the climates of the two coasts, and geographical distribution. 

 Probably these influences alone are the causes why many of the Lam- 

 bay plants do not or could not exist upon Inish-Bofin. On the other 

 hand many of the Inish-Bofin plants which do not occur upon Lambay 

 are absent, in all likelihood, simply from surface conditions and the 

 want of sufficient water. 



Prominent amongst them are : — 



Rammcuhis heterophyllus, et vars., Potamogeton piisillus, 



Drosera rotundifolia, P. natans. 



Myriophyllmn alterniflorum, P. polygonifolius, 



GaJitim palustre, Phragmites communis, 



Ifontia fontana, Eleocharis palustris, 



Ifenyantlies trifoliata, Carex ampidlacea, 



Polygonum am^diihium, Equisetum limosum. 

 Nartheciuvi ossifragum, 



These are all found — for instance, upon the adjacent promontory of 

 Howth, and are unimportant for the purpose which I have in view. 

 They will be omitted in my comparative list as being merely acciden- 

 tal absentees. 



"While upon this subject I will venture to make a remark on the 

 comparison which Mr. More institutes in the above-mentioned "Re- 

 port" between the flora of Inish-Bofin and that of the Isles of Aran, 

 Galway Bay ; taking his data for the latter from a list published by 

 me in 1 875 — a list which is confessedly incomplete. In that publication 



