18 AMi:ni( AS Mi'SJAM (U'lDK LKAFLETS 



survivals. The perfect skull and ja\v> of T. producius in the end case 

 illustrates the primitive features of these Miocene mastodons. 



The oldest mastodons from this country are fnjui the Middle Miocene 

 (Merifchippus zone), and are loo fra«:nicntary to base any important con- 

 clusions u|)on their characters. They are shown in the wall case. T. euhif- 

 podon of tlie Tpjx'r Miocene and early Pliocene is well illustrated by the 

 type sj)ecimen. T. serridens (very close to T. tiiricensi.s of Europe) of the 

 I'pper Miocene and T. hrcridens of the Middle Miocene repre.sent the 

 ZlJ(/()l()ph()d()Nf <rroui), ap|)r()achin<i: the American Mastodon. 



Dinotherium. This extinct jjroboscidean is found only in the Miocene 

 and Pliocene of the Old World, and is very different from the contemporary 

 mastodons. The cheek teeth have but two cross crests, except for the 

 first molar which has three. The tooth row in the adult has five or six 

 teeth, the premolars being retained while the true molars come into use. 

 There are no u})})er tusks, and the lower tu,iks are large, stout, and curve 

 downward to a right angle with the tooth-row. The skull has the general 

 form of the later mastodons, and the animal undoubtedly had a long and 

 hea\y trunk. The body and limbs were proportioned much as in the 

 American Mastodon. Dinotherium is chiefly found in the Miocene forma- 

 tions of Europe. A gigantic skeleton discovered in the Pliocene of Rou- 

 mania exceeds the largest American mastodons in size. Smaller species 

 are also found in Algeria and Tunis, in British East Africa, and in India. It 

 is unknown in the Xew World. 



Casts of palate, jaws, teeth and forefoot of different species of Dinoth- 

 erium, chiefly from the Warren Collection, are shown in the Museum 

 exhibit. 



V. THE EARLY TERTIARY ANCESTORS OF THE MASTODONS. 

 Genera Palaeomastodon, Moeritherium. 



PAL.EOMASTODOX is chiefly known from the Lower Oligocene of 

 tlie Fayiim district in Egypt but fragmentary remains have been 

 recently found in the Gaj horizon of northern India, the lowest 

 fossiliferous level of the great series of the Siwalik Hills. Its discovery 

 and descrij)tion are due to C. W. Andrews of the British Museum. It 

 is uncpiestionably a j)rimitive proboscidean, much smaller and more 

 generalized than the earliest mastodons but showing clearly the especial 

 characteristics of the order. 



The upper tusks are small, down-curved, with enamel over the whole 

 outer surface. The lower tusks are small, s])atulate, and both upj)er and 

 lower tusks have deflnite roots instead of growing from j)ersistent pulps 

 as do those of all later proboscideans. 



