NOTES ON THE KEINDEER AND HIPPOPOTAMUS. 161 



that which to-day constitutes our continent were covered by the then existing 

 seas, the limits of which are nearly everywhere indicated by the great Erratic 

 Formation. What was not quite submerged probably formed no more than a large 

 archipelago, with perhaps certain peninsulas. Hence we can realize for that period 

 all the advantages possessed by marine climates under mean latitudes. 



"This hypothesis, which attributes to the Europe of the glacial period a 

 climate milder, and less excessive in its extremes, than that which to-day favours 

 our so-called temperate regions, will be accepted with difficulty by those geologists 

 or palaeontologists who have assumed that many of the great Quaternary Mammals 

 must have perished by reason of the extreme cold. 



" We may note that the majority of those Mammals which are now accepted 

 as characteristic of the Quaternary Period (that is to say, Elephas primigenius, 

 Hippopotamus major, three of the above-mentioned Rhinoceroses, &c.), and which 

 appear to have retired before the epoch of the greatest extension of the glacial 

 conditions in Europe, must have weathered that supposed climacteric safe and 

 sound. In fact, their remains have very often been found in gravel and alluvium 

 of valley -bottoms, as well as in cave-deposits, attested by the majority of geologists 

 as more recent than the great Northern Erratics. 



" It will be more rational, it seems to us, to suppose that after the retreat of the 

 Glacial sea, and from the period when Europe, thus enlarged, recovered a conti- 

 nental climate, the increased heat of the summers forced the Reindeer and Musk- 

 ox to migrate towards arctic latitudes, more in consonance with the requirements 

 of their temperaments. The Chamois, Ibex, and Marmot, for the same cause, 

 ceased to inhabit the plains of Central Erance and took refuge on the tops of the 

 Alps and Pyrenees. On the other hand, the disappearance or extinction of the 

 Hippopotamus, of certain species of Rhinoceros, and of the great Carnivores, 

 whose congeners have migrated towards tropical regions, may have been caused 

 by the coldness of our winters having become too excessive for the exigencies of 

 their organization. 



" We conclude with a remark having particular reference to the fossil fauna of 

 caverns in South-eastern Erance. It has been seen* that, in the Maritime Alps, 

 the Marsf cavern failed to yield to M. Bourguignat any remains of Reindeer; the 

 absence also of that animal from the cave of Rigabe (Var) has been verified by 

 M. Marion $ ; and the fact is not to be lost sight of that the Reindeer does not 



* In the earlier part of this Memoir by M. Lartet, ' Ann. Sc. Nat.' ser. 5, Zoologie, vol. viii. p. 158. 



t " So called after M. Mars, the proprietor." 



J " Premieres observations sur 1'anciennete de 1'Homme dans les Bouches-du-Khone : 1867." 



