206 BEITISH AND EUROPEAN FOSSIL ELEPHANTS. 



and weighed according to the relative value of the facts. That 

 which is furnished by the niollusca has been everywhere 

 abundantly investigated. I shall now briefly examine the 

 mammalian aspect. In the Italian Pliocenes, where the fauna 

 is most concentrated, two Mastodons and three Elephants, 

 with probably two Rhinoceroses and one Hippopotamus, 

 are met with as leading and characteristic forms. All the 

 Proboscidean forms are not uniformly distributed through- 

 out ; sometimes three or four, and sometimes two, or only 

 one, of the species are met with, but in every instance accom- 

 panied by Rhinoceros leptorhinus, and Hippopotamus major. 

 The presence or absence of the leading species of Mastodon, 

 namely, Tetralophodon Arvemensis, does not appear to be of 

 positive significance, since it has either not been found, or 

 only very rarely, in the Pliocenes around Pome, where the 

 same fossil elephants, Rhinoceros and Hippopotamus,with their 

 associates, occur, as in the Sub-Apennine beds proper. In 

 the English deposits, taking the range from the Crag up to 

 the fluviatile beds of Grays Thurrock, four of these fossil Pro- 

 boscidea, with the same Rhinoceros leptorhinus and Hippopota- 

 mus major, are met with. 1 The two latter pachyderms occur 

 uniformly throughout from the level of the submerged Norfolk 

 lignite bed on to Grays Thurrock. Of the Proboscidean forms, 

 Euelephas antiquus occurs everywhere from the Red and Nor- 

 wich crags, through the submerged forest and Norfolk Lacus- 

 trine clays ; the Brackelsham ' mud-deposit ;' and the Thames 

 fluviatiles at Grays Thurrock, Brentford, and other localities. 

 Loxodon meridionalis occurs in the Crag and in the Norfolk 

 clays along with Euelephas antiquus. But it has not yet been 

 met with in the Thames fluviatiles, although occurring in a 

 corresponding deposit at Chartres in Prance, and appa- 

 rently in some fluviatile beds in Staffordshire or the contiguous 

 central counties. Loxodon priscus has only been found at 

 Grays Thurrock in company with Euelephas antiquus ; and 

 Tetralophodon Arvemensis, in the Red and Norwich Crag, 

 along with Loxodon meridionalis and Euelephas antiquus. 



There is no obvious reason in nature why more importance 

 should be attributed to any one of these Proboscidean forms 

 than to another, as tests of geological age. The Crags con- 

 tain one Mastodon and two Elephants, common to them and 

 the Sub-Apennine beds of the Astesan ; while Grays Thur- 

 rock contains two Elephants, with Rhinoceros leptorhinus and 

 Hippopotamus major, common to it and the beds of the 

 Astesan and Lombardy. These facts would seem to me to 

 be conclusive that all these Pliocene alluviums supported the 



1 This was written in 1857, before the Author separated S. Etruscus and B. 

 hemitoechus from the R. le-ptorhinus of Cuvier. — [Ed.] 



