DINOTHERUD& 435 
and pandionis, from India ; M. americanus, obscurus, and productus, 
North America; and M. cordillerwm and humboldti, South America. 
(2) Tetralophodont series—M. arvernensis, M. longirostris, from 
Europe ; M. latidens, sivalensis, and perimensis, from India ; AZ. mari- 
jficus, from North America. Adastodon arvernensis and M. longirostris, 
together with a trilophodont species, occur in the crag-deposits of 
Norfolk and Suffolk. 
Family DINOTHERIID. 
An extinct family distinguished from the Elephantide by the whole 
series of permanent cheek-teeth being in use at the same time. 
Dinotherium4—Dentition of adult: i %, ¢ 8, p 3, m 3=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 gr ‘eatly 
thickened and deflected beak or pro- 
Iongation of the symphysis. In section 
they do not show the decussating striz 
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 Fic. 189.—Skull of Dinotherium 
of the permanent molar series: 2, 2, 3, feet seg a aa 
2,2. The three ridges of the first true Le ee aw eon 
, $ Pp) p, 3, 4, pre : 
molar are constant in both upper and 12 4 molars. 
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). 
