208 MR. E. T. NEWTON ON THE VERTEBRATE [May 1 894, 



Reid, 1 and it is interesting to see how far the material found at 

 Ightham confirms, or militates against, such a possibility. The 

 Arctic lemming and the Arctic fox are now restricted to the far 

 north and to Arctic conditions. The voles, although some of them 

 are living in temperate regions, all extend far to the north, and 

 two of them (Microtus ratticeps and M. gregalis) are characteristic of 

 desert or steppe conditions. The moles and shrews, though living 

 in temperate countries, extend far to the north in Europe and Asia, 

 and may well have existed in Britain in a cold or steppe climate. 

 The species of bats which have been found likewise have a wide 

 distribution, and most, if not all, range to 60° of north latitude. 

 The common hare, which extends southward, is also found living 

 in the north of Russia. The pika (Lagomys pusillus) is a Siberian 

 and South Russian species, and with the Spermophilus is very 

 strong evidence in favour of steppe conditions. The mammoth and 

 woolly rhinoceros are known to have lived in the far north, 

 although their recent representatives are tropical animals. The 

 reindeer is now an inhabitant of the far north. The red- and 

 roedeer have a wide range, but the latter is essentially a South 

 European form. The brown bear and the common fox extend 

 far into the north, while the Arctic fox, as already noticed, is 

 found only in the northern icy regions. 



The hyaena found at Ightham seems to be identical with the 

 Pleistocene species, which is now living in tropical Africa, and is 

 the one conspicuous form at Ightham which, when compared 

 with the associated species, seems to be so strikingly out of its 

 latitude. However, as is well known, there are species from other 

 Pleistocene localities which seem likewise to indicate a warmer 

 climate — namely, the lion, hippopotamus, and probably the re- 

 maining species of rhinoceros and elephant. But besides these 

 must be noticed two other species not found at Ightham, which 

 point in an opposite direction — namely, the musk ox and the 

 Saiga antelope, one of which is altogether an Arctic species, while 

 the other is just as definitely characteristic of the Steppes. 



Whatever may be the cause, the Pleistocene fauna, as found in 

 the Brick-earth, Gravel, and Cave-deposits, seems to be of a mixed 

 nature, the species finding their nearest allies at the present day 

 living under widely diverse climatic conditions. Some of the 

 Pleistocene species thus indicate extreme cold, others point dis- 

 tinctly to steppe conditions, while a third series seems just as 

 strongly to prove the prevalence of a warm climate. 



These difficulties wiU doubtless eventually be removed, but in 

 the meantime too much stress must not be placed upon the range 

 of recent animals as an indication of that of the past, seeing that 

 there are many circumstances besides climate which help to deter- 

 mine the distribution of species, circumstances concerning which we 

 have, at present, but little information. 



1 « Natural Science,' vol. iii. (1893) p. 367. 



