56 



Proceedings of the Royal Irish Academy. 



but otters fall in with various Types of Distribution, and as this is no 

 doubt in most cases tbe effect not of chance, but of soil or climate, it 

 ■will be worth classifying them. Leaving out of account species which 

 h^ave a restricted range, such as Senecio squalidus and Stratiotes aloides, 

 the aliens of well-marked range run as follows : — 





Central — 





Arenaria tenuif olia. 



E Matricaria discoidea 

 Marginal — 



— 



Lychnis Githago, 

 Inula Helenium, 

 Silybum Marianum, 

 Centaurea Cyanus, 

 Cicborium Intybus, 

 Cuscuta Epithymum, 



B Cuscuta Trifolii, 

 E ? Lycium barbarum, 

 — Mimulus guttatus, 

 B Plantago media, 

 E Bromus secalinus, 

 E 



TTltonian — 



E 



EB 

 BE 



Myrrbis odorata, 

 Anchusa sempervirens. 



1 ? Veronica peregrina, 

 E 



Mumonian — 





Senebiera didyma, 

 Valerianella Auricula, 

 Picris hieracioides, 

 Linaria Elatine, 

 minor, 



AE Verbena officinalis, 

 E Marrubium vulgare 

 E Humulus Lupulus, 

 E Narcissus biflorus, 

 E Leucojum sestivum, 



Lagenian — 



E 

 E 

 B 



GE 



Draba muralis 

 Sisymbrium Sophia, 

 Medicago maculata, 

 Lactuca muralis, 



— Campanula rapunculoides, 

 BE Ballota nigra, 

 E Acorus Calamus, 

 E 



Connacian — 



LI 

 E 



E 



AUium Babingtonii, — 





It will be seen that the more successful aliens, other than those of 

 general distribution, are grouped round the margin of the island, 

 especially in the south and east. They reach their minimum in the 

 centre, north, and west. Their distribution, in fact, coincides with 

 that of the " English" plants (fig. 1), to which type belong, as will 

 be seen from the analysis appended to the list, 16 out of 26 classed by 



