456 PREHISTORIC E UR OPE. 



least two horizons, we need feel no surprise to learn that the 

 peat-bogs of the inland districts now and again contain suc- 

 cessive tiers of forest -trees. At the bottom of the bogs, oak 

 or pine, or both, usually occur — the pine occupying the higher 

 levels and more gravelly soil. Higher up in the peat appears 

 a second stratum of timber, consisting chiefly of birch and hazel, 

 but sometimes principally of oak ; and a third buried forest 

 is occasionally found a little higher up, the common tree in 

 which is generally alder or willow. 



Some twenty years ago Mr. Pengelly discovered Betula nana 

 in the freshwater deposits at Bovey Tracey, in Devonshire, and 

 Professor Heer identified other plants, obtained by Pengelly 

 from the same locality, as willows — Salix cinerea and S. repens ? 

 The latter he now thinks is more probably S. myrtilloides. 

 Mr. Nathorst has more recently examined the beds and ob- 

 tained Betula nana, B. alba, Salix cinerea, and other willows, 

 Arctostaphylos uva-ursi — the last-named being a species which 

 does not come farther south than Cumberland and Yorkshire, 

 while Betula nana is confined to the Scottish mountains. 1 



The postglacial mammals of England, exclusive of those 

 which are still indigenous, are brown bear, great Irish deer, elk, 

 reindeer, urus, long-fronted ox, aurochs or bison, otter, beaver, 

 wolf, and wild-cat. Of these, the brown bear was a native 

 of England during and probably for some time after the Eoman 

 occupation. The beaver had become scarce in "Wales before 

 the close of the ninth century, for we find in the Laws of Hywel 

 Dha, where the prices of furs were regulated, that a marten's 

 skin cost 24d., an otter's 12d., and a beaver's 120d. It was 

 still existing, however, towards the close of the twelfth century, 

 and is mentioned by Giraldus Cambrensis as being at that time 

 a native of Wales. The wolf appears to have been extirpated 

 in the north of England in the reign of Henry VIII. The urus 

 and the long-fronted ox probably ceased to be feral in early 

 historic times. The reindeer, the elk, and the great Irish deer 



1 See Philosophical Transactions,1862, p. 1039, and Ofver. af K. Vet.-Akad. 

 Fbrh., 1873, No. 6, p. 17. 



