20G 



ON THE EXTINCT MAMMALIA OF 



Length of the upper true mohar series, 

 Antero-posterior diameter of last true molar, 

 Transverse " " " 



Length of crown, . . . : . 



Antero-posterior diameter of second true molar, 

 Transverse " " " 



Antero-posterior diameter of first true molar, 

 Transverse " " " 



Antero-posterior diameter of third premolar, 

 Transverse " " " ' . 



Antero-posterior diameter of second premolar, 

 Transverse " " " 



Antero-posterior diameter of last lower molar, estimated. 

 Transverse " " " 



Lines. 



35 



13J 



15 



7i 

 13 

 14 

 10 

 11 



6 



9 

 10 



8i 

 17 



8 



ANOPL THEEIDM. 



To this ancient and extinct family, typified by the curious Anoplotherium of the 

 eocene formations of Europe, I have referred the genus Titanotlierium, a huge animal 

 whose remains are characteristic of the lowest bed of the tertiary deposits of the 

 Mauvaises Terres. The remains are associated with those of Hyopotanms, Lopliiodon, 

 and Rhmoceros occidentalis, and the bed in which they are found, marked A in Dr. 

 Hayden's tables, immediately overlies the cretaceous formation of Dakota. 



TITANOTHERIUM. 



This extinct genus appears to be nearly allied with Ghalicotherium, and, like it, 

 approximates the even-toed pachyderms, or Artiodactyla, as previously defined, with 

 the Ruminantia. From the form of its lower true molars, which were first dis- 

 covered, it was supposed to be more nearly allied with the PalceotJierium, and was 

 hence placed among the uneven-toed pachyderms, or Perissodactyla, but the nearly 

 complete dentition of both jaws, since discovered, appear to indicate its position to be 

 as above stated. 



TiTANOTHERIUM PrOUTI. 



The animal thus named was of comparatively huge proportions, and larger than 

 any of those with which its remains are found associated in the miocene deposits of 

 Dakota. A notice of the great extimct pachyderm was first published by Dr. Hiram 

 A. Prout, of St. Louis, who described a fragment of the lower jaw as pertaining to a 



