PALAEONTOLOGY THE river gravels and alluvial deposits, the London Clay and the Cretaceous rocks of Kent are noted for the abundance and fine preservation of their vertebrate fossils ; and a large number of genera and species have been described from the two last- named formations on the evidence of Kentish specimens. The London Clay of Sheppey has in fact furnished practically all our information with regard to the birds which inhabited England during the early part of the Eocene period ; and the vertebrates of the Folkestone Gault are to a great extent unknown elsewhere. The fissure of Pleistocene age at Ightham has revealed the existence at a time when the mammoth and woolly rhinoceros roamed over the south-east of England of a fauna largely composed of species still existing. Of the other Pleistocene deposits in the county perhaps the most important are the gravels at Aylesford and Maidstone and the so-called bone-bed at Folkestone.^ An interesting fact in connection with the county is the discovery of fossil remains of the woolly rhinoceros at Chartham about the middle of the seventeenth century, to which further allusion is made below. The vertebrate fauna from one of the fissures in the Kentish Rag near Ightham, which, as already said, is considered to be of Pleistocene age, has been described by Mr. E. T. Newton,^ and is remarkable for the number of species of the smaller mammals, whose remains are so seldom preserved in formations of this age. The remains include those of several kinds of bats, all apparently referable to existing species ; as well as of the common and the lesser shrew and the mole. The Ightham Carnivora comprise the wolf, fox, Arctic fox {Canis lagopus), wild cat, cave-hy^na {Hycena crocuta spelaa), brown bear, badger, otter, weasel, polecat, and a species regarded as an extinct kind of polecat and named Mustek robusta. The rodents include an extinct species of suslik [Spermophilus erythrogenoides) ; the wood-mouse [Mus sylvaticus), and an extinct species of the same genus named M. lewisi ; six or seven species of voles, some of which are unknown in the living state in Britain ; the Norwegian lemming {Lemmas lemmas) and the banded lemming [Dicrostonyx torqaatus) ; the common pica {Ochotona pusilla) ; the common hare, the mountain hare {Lepus timidas), and the rabbit, the remains of the latter being probably of later age than those of the other mammals. » See S. J. Mackie, Quart. Journ. Geo!. Soc. (185 i) vii. 257. 8 Ibid. (1894) 1. 188, and (1899) Iv. 419. 31
