8 ox THE MAMMALIAIf FAUlSrA OF THE YAL d'aEJSTO. 



wMch is older than the mammal fauna of the upper Val d'Arno. 

 It may therefore be concluded that this species is geologically 

 older in Austria and in Hungary than it is in Italy. The occur- 

 rence of a single species in distant or isolated regions cannot be 

 taken to prove that the strata in which it occurs are contemporaneous. 

 A species can only survive under favourable conditions, among which 

 isolation counts before anything, as in the case of the Myolagus of 

 Corsica and Sardinia. 



§ 7. J^ote ly Prof. Boyd DawJcins. 



In this valuable contribution to our knowledge of the Pliocene 

 mammal-fauna of Italy, Dr. Porsyth Hajor draws attention to the 

 sharp line of definition between the Phocene and Pleistocene, and 

 considers that no species passed from the one to the other in Italy. 

 In this I am unable to agree, because two of the Cervidse, Cervus 

 etueriarum and C. Perrieri^* are undistinguishable from varieties of 

 Deer belonging to the Axis and Rusa type now inhabiting the 

 Oriental region. 



'^ov can I agree with him in viewing the Hi^jpopotamus major of 

 the Yal d'Arno as having been assumed to be identical Avith the 

 living H. amjpJiihius on the strength of a Cuvierian tradition. I have 

 attempted in vain to distinguish between the fossil and the living 

 forms, and after detailed measurements and a careful comparison of 

 those from the Val d'Arno in the British Museum with the living, 

 and after an examination of those in the Museum of the Jardin 

 des Plantes in Paris, I am obliged to believe that they belong to 

 the same species. U. aniphihius must therefore be counted as a 

 living species dating back from the Pliocene age. Numerous 

 Pliocene species, Elephas meridionalis, Rhinoceros etruscus, &c., as 

 I have already pointed out in various papers read before the Society, 

 undoubtedly occur wi situ in the Forest-bed of ISTorfolk and Suffolk, 

 in association with Pleistocene forms, and prove the overlap of 

 the Pliocene and Pleistocene groups. I have also shown t that the 

 Oriental region is that in which the Pliocene mammalia of Europe 

 find their nearest analogues. 



With regard to the nomenclature of Ehinoceros, Dr. Porsyth 

 Major's criticism applies only to the R. leptorhinus of Cuvier, and 

 not to the R. leptorTihitis of Owen, which is the equivalent of the 

 U, hemitoechus of Falconer. 



* Quart. Journ. Geol. Soc. 1878, p. 407. 

 t Ibid. p. 419. 



