1897] THE PROBLEMS OF BRITISH FAUNA :\77 



animals have been recognised which undoubtedly show similar 

 faunistic relationships. Some of these are new discoveries, and 

 are apparently confined to Ireland, such as the millipede Pohy- 

 desmtis gallicus, 1 the earthworms Allolobqphora veneta and A. georgii,- 

 and the weevil Otiorrhynchus auropunctatvs.* Others have long 

 been known as British animals, and their occurrence in the west of 

 Great Britain as well as in Ireland lias probably caused their 

 faunistic import to be overlooked. Such are the snail Helix pisana, 

 the wood-louse Platyarthrus hoffmanseggii, the ground beetle Eury- 

 iifbria complanata, and the weevil Mesites tardyi. Some of these 

 animals are found both in the east and west of Ireland, others only 

 on the east coast. In Great Britain they occur mostly in the 

 south-west, but the last-named is an example of a section which 

 ranges northward into western Scotland. Abroad all are charac- 

 teristic of southern and south-western Europe, while several are 

 found in the Azores, Madeira, and Canary Islands. It is most 

 important to take the foreign range into consideration when assign- 

 ing animals to a distributional type. Just as the Common Hare is 

 spread far to the north in Great Britain, as compared with many 

 other members of the ' Siberian ' fauna, so a number of animals 

 belonging to the South-western fauna range farther to the east than 

 the more typical species of the group. For instance, the slugs 

 of the genus Tcstacella must be referred to the South-western 

 section, when we consider the general range of the genus, though 

 some species occur in our eastern counties. And Dr Scharff would 

 add to this fauna many of our widely distributed species — the 

 Bullfinch among birds, for example. 



He believes moreover that this South-western fauna merges 

 gradually into a ' South-central ' fauna, including the Badger 

 among mammals, and Helix virgata, H. acuta, and H. nemoralis 

 among snails. And to these combined southern groups he is 

 inclined to ascribe the bulk of the Irish animals, even those with 

 a wide range both in Ireland and in Great Britain ; except a few- 

 species that may have invaded the country since it became an 

 island — such as the white butterflies, Pieris brassicae and 

 P. rapae, and the ' painted lady,' Pyrameis cardui, or that have 

 been apparently introduced by man — such as the rats and the 

 house mouse. 



A few remarks are necessary regarding the relative ages which 

 are to be ascribed to these different sections of the British fauna. The 

 South-western group, the most typical members of which are found 

 in the most remote parts of the country, with ranges often discon- 

 tinuous, are evidently the oldest. The ' Siberian ' animals, which 



1 R. I. Pocock, Irish JYaL, vol. ii., pp. 309-312. 2 H. Friend, id., vol. v., pp. 69-73. 



3 G. H. Carpenter, id., vol. iv., pp. 213-218. 



2 D 



