18 OSBORN. 



third superior premolars have double internal cusps. Lissicu 

 as studied by Deperet is mainly middle Eocene but it contains 

 some important Upper Eocene forms, while Egcrkingen has a 

 rich representation of Upper Eocene types. 



The large L. rJiinoccrodcs Riitimeyer, of Egerkingen is, how- 

 ever, not of the Heidenheim type because it has simple upper 

 premolars associated with it ; it is an older representative of the 

 large race of Lopliiodontidcu, 



Maiircnwnt is considered mainly, if not exclusively, of Upper 

 Eocene age. 



General Characters. 



(i). This fauna is much more modern than that of the Gres 

 de Ccsscras, or of the Calcaire Grassier and Isscl ; the great 

 advance in the structure of the teeth especially seen in a com- 

 parison of Propalceotlicriuin and Palcuotlicrinin is proof of mod- 

 ernization. Pal^otherium is now the predominating type of 

 Perissodactyl, although a large form of Lopluodon survives. 



(2). Secondly, the composite beds of Egcrkingen and Lissieii 

 furnish the ancestry of certain types of Gypse Artiodactyla and 

 in these beds we also find certain other forms transitional between 

 the Issel stage and the Gypse stage. 



(3). Thirdly, the Gypse, is a very highly specialized and 

 differentiated fauna including many artiodactyls and other types 

 the ancestry of which is known neither in Europe or America 

 and has not thus far been found in Egerkingen or Lissieu. 



(4). Fourth, the Ligftrien is widely distinct faunally from the 

 American Upper Eocene or Uinta with which it has been here- 

 tofore paralleled. At no period of the Tertiary were the Nearc- 

 tic and Palaearctic faunae so widely separated. In fact a much 

 wider gap exists between Western America and Europe in the 

 Upper Eocene than in the preceding Lower and Middle Eocene 

 or in the succeeding lower Oliogocene. 



The resemblances or parallels with America are mostly lim- 

 ited to one genus of horses [Pachynolop/ms), which occur in both 

 countries, to one Creodont Hycenodon, and to the ancestors of 

 the Canidce and Viverridcs which occur in both countries. 



(5). Contrasts. The Cheiroptera and Insectivora of these two 



