0* 



that their climate is similar to that of the Asturias. "When we turn to 

 the Asturian districts of Ireland, we find more features of geological and 

 physical resemblance to the North of Spain than in any other districts 

 of equal area in Ireland. The influence of climate, which seems of pa- 

 ramount importance in relation to Plants, is very remarkable in the Irish 

 Asturian districts. The author illustrated his views by reference to a 

 Map on which were projected the isothermal lines of mean annual and 

 mean winter temperature for Ireland. These lines were drawn by the 

 aid of observations made at some new stations, in addition to those on 

 which he had to rely when projecting the isothermals already published. 

 Among these stations he especially referred to Galway, from its posi- 

 tion in the "West Asturian district. From the Map, it appears that the 

 greater part of the areas of both of the Asturian districts lie between 

 the annual isothermals of 52° and 51°, and between the winter isother- 

 mals of 45° and 44°. These are the lines of highest temperature in 

 Ireland, and the winter lines correspond almost identically with those 

 belonging to the middle of the province of Asturias itself. On the other 

 hand, the summer temperature of the Irish Asturian districts is from 

 57°. 5 to 59°. 3 respectively, and therefore from 6° to 8° lower than that 

 of the North of Spain ; whence it follows, that, if Plants were intro- 

 duced into an Asturian district from Spain, some of which required a 

 warm summer, while others required only a mild winter, the former 

 would die, while the latter might survive, and even spread over exten- 

 sive areas. The condition of great summer warmth seems to be espe- 

 cially required for annuals belonging to southern climes, as the ripening 

 of the seeds would be inevitably checked by a single cold and wet sum- 

 mer. The growth of perennials appears to depend principally on the 

 condition of winter temperature, as these Plants may spread by roots 

 and suckers. After referring to the generally admitted fact of the 

 moisture of the climate of Ireland, the author concludes, from observa- 

 tions made at Galway, Innishgort, in Clew Bay, and Lough Corrib, that 

 the annual rainfall in the West Asturian district must at least exceed 

 fifty inches ; while observations made at Yalentia, Killarney, Cahir- 

 civeen, and Castletownsend show that the fall is probably still greater 

 in the So nth- West district. 



Corresponding conditions exist with regard to the relative hu- 

 midity of the air. If, as before supposed, different varieties of Plants 

 from a southern clime were by accident introduced into our Asturian 

 districts, for some of which moisture was more favourable than to 

 others, the former would have a far greater chance of becoming widely 

 spread, while the growth of the latter might be checked instead of being 

 promoted. 



The influence of cultivation in promoting or checking the introduc- 

 tion of wild Plants into the Asturian districts was next discussed. It 

 appears from returns furnished to the Registrar- General of Ireland dur- 

 ing five years, that the greatest proportion of w r eedy ground was ob- 

 served in the Asturian districts ; and from returns made during several 

 years of the relative areas under tillage, pasturage, and in a totally un- 



