THEIR GEOLOGICAL AGE. 191 



action of the sea ; and as the cliffs are undermined, the re- 

 mains of different ages are mingled together on the beach 

 below. The waves wash away the incoherent matrix, leaving 

 the fossil bones in adventitious association; and they are 

 thus presented to the palaeontologist, either in museums or 

 by collectors, under circumstances in the highest degree 

 deceptive. If we pass inland, say, to the Valley of the 

 Thames, the ' high ' and ' low level ' gravels, the brick- 

 earths, and other fluviatile or subaerial deposits are ob- 

 served by the geologist thickening here and thinning out 

 there, and apparently intercalated with such subtle compli- 

 cation that their stratigraphical extraction satisfactorily 

 has been admitted by leading English geologists to be a 

 matter of great difficulty. In some cases the remains of the 

 older epoch are exhibited at the high level, while the more 

 modern forms occur in the lower. The consequence of all 

 this has been that it has long been a point of accepted belief 

 among English geologists, that the long-haired and woolly 

 Mammoth of Siberia had lived back to be a contemporary of 

 the Mastodon in the Crag; while the Hippopotamus major 

 had lived on from the period of the submerged, forest, if not 

 from the Crag, to be a contemporary of the Mammoth, the 

 Siberian Rhinoceros, and the Musk Ox, upon the superficial 

 gravel of the Valley of the Thames. 



The obvious way of dealing with cases of this nature is 

 to examine the conditions where they are most simple, and 

 then to apply the results to the more complex instances. I 

 shall adopt this course in the remarks which I have to offer 

 on the European fossil Elephants ; and first in regard to the 

 Pliocene forms. 



The most instructive instance with which I am acquainted 

 of the occurrence of the greatest number of Proboscidean 

 fossil species in the same deposit, under circumstances that 

 admit of no doubt as to their common age and association, 

 is one to which I have referred in the former part of 

 this communication, namely, that of the Mastodon (Tetra- 

 lophodon) Arvernensis described by E. Sismonda. The entire 

 skeleton of the animal, spread out, was disclosed by a 

 railway cutting between Dusino and Villafranca, at a depth 

 of about twenty-six feet below the surface. In the same 

 locality and in the same stratum, but a little apart from 

 the skeleton of the Mastodon, were found fossil grinders of 

 E. (Loxodon) meridionalis, Rhinoceros leptorhinus,* with stags' 

 horns ; and close upon the surface the skull of a Lagomys. 

 In the fluvio-lacustrine matrix, along with these remains, 

 were found species of Unio, Helix, Paludina, and Clausilia. 



1 Subsequently B. Etruscns, Falc— [Ed.] 



