PA L.-EO THERIIDjE 



375 



with the Tapiridce ; the fourth and probably the third upper pre- 

 molar approximating in structure to the molars ; the upper molars 

 have conical outer columns. Helaletes is another closely allied 

 form, with similar premolars, but with the outer columns of the 

 upper molars flattened. 



Family PAL^EOTHERIID.E. 



Molars (Fig. 155) brachydont, with the valleys between the 

 ridges never filled with cement ; upper premolars either simpler than 



FIG. 154. Restoration of Palceotherium (Upper Eocene). After Cuvier. 



or, -as complex as the molars; lower molars with crescentoid ridges, 

 and the last of the series with or without a third lobe. Outer 

 columns of upper molars flattened. 

 Orbit (at least usually) confluent 

 with temporal fossa. Three digits 

 on each foot. This family in- 

 cludes extinct genera ranging from 

 the Middle and Upper Eocene to 

 the Miocene, and passes so gradu- 

 ally into the following one that the 

 maintenance of the two can only 

 be supported on the ground of 

 convenience. The typical genus, 

 Palceotherium, was made known to 

 science in the early part of the T 



* JIT" , i Palceotherium magnum. (Alter uwen.j /, /, 



present century by Cuvier, Who External surfaces of outer columns; a, postero- 



restored the skeleton (Fig. 154) external column (metacone); 6, antero-ex- 



* 1 1 i 11 M ii, fj_i temal column (paracone) i c. postcro-intenial 



With a Short neck like that OI the column (hypowne) d, antero-internal column 



Tapirs, although it has been Sub- (protocone) ; i, anterior intermediate column 



Sequently found that the neck (protoconule); e, median valley; g, posterior 



was considerably longer. This 



genus (which may be taken to include Paloplotherium) ranges from 



FIG. 155. A half- worn right upper molar of 

 (After Owen.) /, /, 



