DINO THERIID& 



435 



and pandionis, from India ; M. americanus, obscurus, and productus, 

 North America ; and M. cordillerum and humboldti, South America. 

 (2) Tetralophodont series M. arvernensis, M. longirostris, from 

 Europe ; M. latidens, sivalensis, and perimensis, from India ; M. miri- 

 faus, from North America. Mastodon arvernensis and M. longirostris, 

 together with a trilophodont species, occur in the crag-deposits of 

 Norfolk and Suffolk. 



Family DINOTHERIID^E. 



An extinct family distinguished from the Elephantidce by the whole 

 series of permanent cheek-teeth being in use at the same time, 



Dinotherium. 1 Dentition of adult : i &, c ft, p f, m f = 22 ; all 

 present at the 

 same time, there 

 being no hori- 

 zontal succes- 

 sion, but the 

 premolars re- 

 placing milk- 

 teeth in the or- 

 dinary manner. 

 The presence or 

 absence of upper 

 incisors has not 

 yet been clearly 

 ascertained. 

 Lower incisors 



large, conical, descending, and slightly 

 curved backwards, implanted in a greatly 

 thickened and deflected beak or pro- 

 longation of the symphysis. In section 

 they do not show the decussating striae 

 characteristic of Mastodons and Ele- 

 phants. Crowns of molars carrying strong 

 transverse, crenulated ridges, with deep 

 valleys between, much resembling the 

 lower ones of the Tapirs. Ridge-formula 

 of the permanent molar series : 2, 2, 3, 

 2, 2. The three ridges of the first true 

 molar are constant in both upper and *> 2 > 3 > 

 lower jaws, although it is quite an anomalous character among 

 Proboscideans for this molar to have more ridges than those which 

 come behind it. The last milk -molar has also three ridges, the 



1 Kaup, Isis, vol. xxii. p. 401 (1829). 



Fie. 189. Skull of Dinotherium 

 gigaiiteum, from the Lower Pliocene 

 of Eppelsheim, Hessen- Darmstadt. 

 (After Kaup.) p, 3, 4, premolars ; 



