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 Egcrki)igcn has a 

 rich representation of Upper Eocene types. 



The large L. rliiiioccrodcs 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 Lophiodoiitidcc. 



JMaurcniout is considered mainly, if not exclusively, of Upper 

 Eocene age. 



General Characters. 



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

 de Ccsscras, or of the Calcairc Grossicr and Isscl ; the great 

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

 parison of Propaht^otlicriitui and PaUcothcrium is proof of mod- 

 ernization. Paljeotherium is now the predominating type of 

 Perissodactyl, although a large form of Lophiodon survives. 



(2). Secondly, the composite beds of Egcrkingoi and Lissicu 

 furnish the ancestry of certain types of Gypsc Artiodactyla and 

 in these beds we also find certain other forms transitional between 

 the Isscl stage and the Gypsc stage. 



(3). Thirdly, the Gypsc, is a v^ery highly specialized and 

 differentiated fauna including many artiodactyls and other types 

 the ancestiy of which is known neither in Europe or America 

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



(4). Fourth, the Ligurien 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 {Pacliynoloplms), which occur in both 

 countries, to one Creodont HytE)iodoii, and to the ancestors of 

 the Canidcu and Vivcrridce which occur in both countries. 



(5). Contrasts. The Cheiroptera diXid Inscctivora o( thesQ two 



