108 MASTODON ARVERNENSIS. [Ch. XTT 1 



according to the latest investigations, to 89 per cent., whereas in the 

 Eed Crag it does not exceed 60 per cent. 



Among the accompanying remains of mammalia are those of a 

 Mastodon, a portion of the upper jawbone with a tooth having been 

 found by Mr. Wigham at Postwick, near Norwich. This species has 

 also been found in the Red Crag, both at Sutton and at Felixstow, 

 and was till lately regarded as an Upper Miocene or Falunian species ; 

 and under this persuasion, calling it M. angustidens, on the authority 

 of Professor Owens, I suggested that its' remains might have been 

 washed out of older strata into the Crag, just as we sometimes ob- 

 serve London Clay and Chalk fossils introduced into the same de- 

 posit. But Dr. Falconer, who has devoted many years to the study 

 of the fossil and recent Proboscideans, has shown that the fossil is a 

 Pliocene species, first observed in Auvergne by MM. Croizet and 

 Jobert, and named by them Mastodon arvernensis. Cuvier did not 



Fig. 148. 



Mastodon arvernensis (Norwich Crag, Postwick, also found in Eed Crag, see p. 202) ; third 

 milk molar, left side, upper jaw; grinding surface, nat. size. Newer Pliocene. 



adopt this name, for he had seen but a few specimens from Auvergne, 

 and he confounded them with M. angustidens. The entire skeleton 

 of both these Mastodons having now been obtained, they are found 

 to be referable to two distinct sub-genera. The Crag ' fossil belongs 

 to the Tetralophodon of Falconer, a sub-genus of which five species 

 are known, so called because there are four ridges in the penultimate 

 true molar as well as in the two teeth which are placed immediately 

 before it in both jaws. The Mastodon angustidens, on the other 

 hand, belongs, with six other species, to the section called Triloplio- 

 don, in which the corresponding teeth have each three ridges ; and is, 

 according to MM. Lartet and Falconer, characteristic of the Faluns of 

 Touraine, as well as of Sansan at the foot of the Pyrenees, and sev- 

 eral other Miocene localities. 



The Mastodon arvernensis, says Dr. Falconer, is the only one yet 

 found in England. It abounds with the Hippopotamus major in the 



