62 GEOLOGICAL MEMOIKS. 



nine formations. The species which Kved during the PUocene period, 

 and were contemporary with this grand pheenomenon, are therefore 

 those whose remains we should expect to find beneath the oldest 

 basaltic eruptions. 



III. The third and most recent fauna, called by M. Pomel the 

 Diluvian, comprises the species of all the localities now known, ex- 

 cepting those previously named : the beds are numerous, and scat- 

 tered over Auvergne in the valley of Limagne. They are unques- 

 tionably synchronous with the great dilmdal or erratic phsenomena ; 

 for they contain the same species as the beds of that epoch, though 

 quite diiferent from them in geological characters, being usually the 

 result of the slow and partial degradation of calcareous and basaltic 

 hills. 



This division differing from that of the naturalists of Auvergne, 

 has been opposed by them, and especially by M. Bravard, who recog- 

 nises four distinct faunas : the lacustrine Miocene ; the Pliocene, or, 

 as he terms it, the Mastozoic, characterized by the presence of the 

 mastodon, and the absence of the elephant, horse, hippopotamus, 

 &c. ; the Elephantine, characterized by the presence of these last 

 genera ; and lastly the Diluvian, in which they as well as the rhi- 

 noceros are wanting. But as the species common to the two latter 

 faunas are, as M. Pomel asserts, the most important, and the ab- 

 sence of the genera named depends upon the geological conditions 

 under which they were entombed, these two faunas differ no more than 

 the MoUusca of two beds reposing upon one another, which though 

 of different mineralogical composition, yet belong to one subdivision 

 of one and the same group which no geologist would propose to 

 separate. 



Two fossil faunas may be called distinct, when (many species of 

 each being known) they admit of comparison by their types being 

 generically analogous, though specifically distinct : in such case there 

 are two parallel series of species more or less resembling, composing 

 two zoological groups : those species which appear to be common 

 must either be such as are doubtful from our imperfect acquaintance 

 with them, or from their osteological character not being strongly 

 marked, as is the case with the hare, the horse, &c. of the existing 

 fauna. Now the two faimas proposed by M. Bravard under the 

 names of Elephantine and Diluvian do not answer this descrip- 

 tion, since the species which pass from the one to the other are 

 numerous, well-characterized, and important in many points of view. 

 M. Pomel proceeds to establish the existence of two distinct faunas, 

 the Pliocene and Diluvian. First considering the Carnivora, he 

 shows that the Ursus Arverniensis of Etouaires is distinct from that 

 of Champeix and Neschers. The Canis spelceus of Juvillac, C. Nes- 

 chersensis of Anciat, and the Fulpes fossilis found in many other 

 caverns, are very distinct from the Canis megamastoides of Mont 

 Perrier. The Martins of the Diluvium are very different from 

 M. lutroides of Pomel, and from the Zorilla lately discovered in Arde 

 by M. Bravard. The Otter from the same locality {Lutra Bravardi) 

 cannot be confounded with the cavern species which does not occur 



