334 NATURAL SCIENCE [May 



Arde, Peyrolles, and other localities in the Puy-de-D6me, France ; 

 from Eoussillon and Montpellier (Herault), where the Lower and 

 Upper Pliocene faunas are not quite clearly distinguished ; and from 

 the iSTorwich Crag of Norfolk. There are still traces of the apes 

 in southern France. Among the Carnivora, Hyaenardos is just 

 becoming extinct, and is being replaced by small bears of the 

 genus Ursus ; while the species of sabre-toothed tiger, or Machaerodus, 

 are now very large. The true beavers {Castor) and other char- 

 acteristic modern genera of Eodentia appear for the first time, and 

 there is a large beaver-like animal, Trogontherium. Mastodon occurs 

 for the last time, and Elephas now appears with tlie gigantic E. 

 meridionalis. There are also true oxen {Bos, Lcptohos) and deer of 

 existing genera {Cervus, Cervulus) ; while a typical hippopotamus, as 

 large as the recent H. amphibius, is not uncommon. The tapirs 

 have already disappeared, but rhinoceroses survive {B. etruscus) ; 

 and for the first time there is a completely evolved one-toed horse 

 {E. stenonis). 



The Cromer Forest Bed 



At the close of the Pliocene period Britain was still connected 

 with the adjoining continent, and an interesting remnant of the 

 mammalian fauna of this part of Europe at the time is preserved 

 in an old land surface and associated deposits now exposed in the 

 cliffs of Norfolk, especially in the neighbourhood of Cromer. This 

 is the so-called Forest Bed Series. The mammals found here are 

 chiefly those of the typical Pleistocene fauna ; but a few still 

 survive from the Upper Pliocene, such as a gazelle, some deer with 

 very large antlers allied to the Cervus dieranius of the Val d'Arno, 

 Bhinoceros etruscus, Elephas meridionalis, and Trogontherium. The 

 Forest Bed fauna is thus intermediate in character between the 

 Pliocene and the Pleistocene ; and a similar mingling of forms has 

 been observed in certain local deposits both in France and Italy. 



Pleistocene 



The Pleistocene mammalian fauna of Europe is very remarkable. 

 It does not include many forms which have subsequently become 

 extinct ; but throughout the central and north-central parts of the 

 continent there is a curious mingUng of northern, eastern, and 

 southern types which it seems difficult to explain. The remains of 

 this fauna are met with in the surface deposits and caverns of 

 Britain, so far north as Yorkshire, quite as abundantly as on the 

 continent ; so that the bed of the North Sea and the Straits of 

 Dover must still have been an open valley, and our island remained 

 part of the mainland. The northern animals include the reindeer 

 and musk-ox, which wandered as far south as the Pyrenees ; the 



