626 . Reviews — Br. R. F. Scliarff — European Fatma. 



" There are also some British mammals of which we have no fossil 

 history, at least of which no remains have as yet been found in 

 these Islands. Sucli a one is the harvest-mouse (Mas minutus). It 

 has a somewhat restricted range in England, and only just crosses 

 the Scottish border in the east. From the rest of Scotland and from 

 the whole of Ireland it is absent. To judge from this distribution, 

 in connection with the fact of its being unknown as a British fossil 

 species, it is probably a late immigrant to England, and has not had 

 time to spread, through Scotland at any rate. But it is also absent 

 from Scandinavia, from the Spanish Peninsula, from almost the 

 whole of Italy and the Alps, as also from the Mediterranean islands, 

 whilst the little mouse occurs abundantly right across Siberia. We 

 shall learn more about centres of dispersion later on ; meanwhile 

 I should mention that such a distribution indicates that the harvest- 

 mouse has most likely originated in the east, and has spread from 

 there westward in recent geological times. 



" Conchologists have long ago been acquainted with the fact that 

 many molluscs, for example the so-called 'Stone-cutter' Snail [Helix 

 lajiicida) and the 'Cheese Snail' [Helix obvoJuia), have a very 

 restricted range in the British Islands. Both are entirely absent 

 irom Scotland and Ireland, the Cheese Snail being confined to 

 S<juth-Eastern England. The Stone-cutter has rather a wider range, 

 is even known from a Welsh locality, and is met with as far north 

 as Yorkshire. Their distribution would indicate, therefore, that 

 while both are recent immigrants the Cheese Snail is probably the 

 last comer. This supposition is in so far supported by fossil 

 evidence, as the latter is unknown in a fossil state, whilst the 

 Stone-cutter has been described by Messrs. Kennard & Woodward 

 as occurring in the cave deposit known as Ightham-fissure, and also 

 from several English Pleistocene and Holocene deposits. The Stone- 

 cutter can scarcely be looked upon as a very recent immigrant in 

 the light of this evidence, though we have no proof of its having 

 ever had a much wider range in the British Islands than it has to-day. 



" Among the lichens, which so abundantly cover the rocks and trees 

 in Soutli- Western Ireland, and which impart such a characteristic 

 feature to the scenery, we find a beautifully spotted slug {Geomaculnn 

 maculosns). It is a stranger to the rest of the British Islands, and, 

 indeed, occurs nowhere else in Northern Europe. We have to travel 

 as far as Northern Portugal before we again meet with it ; it is there 

 also that its near'est relations live. 



"Many more similar examples might be quoted, but enough, 

 I think, has been said to show that the British fauna is made up 

 of several elements whose original homes may be widely apart and 

 in difl^erent directions. We have fossil evidence that some of the 

 Northern species, and also a few of the southern ones, have become 

 extinct within comparatively recent times, others are apparently 

 on the verge of extinction, whilst many not only maintain their 

 position in the constant struggle for existence, but are even extending 

 their range." (p. 5.) 



We are glad that Dr. Scharff has given us his views on the history 



