206 The Flora of Ireland. 



The association of plants with certain kinds of soil is not 

 even alluded to, although the way has been led by Mr. Foote,* 

 who has shown that in " The Burren," county Clare, as in most 

 districts, there is a close connection between botany and geo- 

 logical strata ; and Mr. Tate f has pointed out the peculiar 

 attachment of many species in the north of Ireland to certain 

 rocks and soils. As the Gyhele is but the sum of all the 

 local floras, so we may reasonably expect that facts of this 

 kind should have been collated, and some general law have 

 been deduced. 



If some regard had been paid to this department of the 

 Gyhele, the parcelling out of the island into districts would 

 have been made more in accordance with the physical and 

 petro graphical features of the surface than has been done. 

 Such an investigation has led the writer to differ from the 

 authors who attach the county Down to the counties of Derry 

 and Antrim to form their District 12. Now, geologically, 

 Down is very differently constituted from Derry and Antrim ; 

 in the former palaeozoic rocks prevail, yielding light and warm, 

 and, in a few localities, calcareous soils ; whereas the basaltic 

 rocks occupy the greater portion of the surface of Derry and 

 Antrim, with keuper marls and liassic shales beneath the 

 escarpments of the volcanic masses. The soil of this area is 

 cold and heavy, excepting here and there along the coast, where 

 sand and gravel are met with, in which case a marked group 

 of plants accompany the same. Much of the district. is, more- 

 over, elevated above the agral zone, and is greatly encumbered 

 with wet peat bogs ; in the county Down, this is not much the 

 case, and the surface is varied by the occurrence of swamps. 



In the Gyhele I find that 112 species are recorded in 

 the counties Antrim and Deny, which are unknown in Down, 

 and that 25 species met with in that county are wanting 

 in Derry and Antrim ; the number of species in common being- 

 about 650. This partial incommunity of species between 

 Down and Antrim is real, and cannot be reasoned away on 

 the grounds that the latter county has been better worked ; 

 it is due to physical features, soil, and geographical position. 

 For it is significant that the county Down is richer in species 

 of the Germanic and English types of vegetation, whilst Antrim 

 and Derry contain a superior number of Scottish and High- 

 land plants; some of which, however, though eminently ch 

 racteristic of the northern counties, pass into Down, and via 

 versa. As, for example, Lamium intermedium (the frequency 

 of the occurrence of this plant appears unknown to the editors), 

 which occurs from Magilligan, county Derry, along the coast 



* On the Distribution of Plants in Burren. Traus. Hoy. Ir. Acad. 1862. 

 f Flora Belfast 'iensis. 1863. 



