THE EOCENE OF EUROPE AND NORTH AMERICA 143 



supposed by Rlitimeyer to be related to the taeniodont edentates of 

 America, is now regarded by Stehlin as related to the aye-aye (Cheiromys) 

 of Madagascar. The rodents also (Plesiardoniys) are remotely related/ as 

 well as the primates, or lemuroids. The most American type of animal in 

 the European Middle Eocene is perhaps the little carnivorous creodont 

 Sinopa of Egerkingen, a representative of the family Hyajnodontidae, and, 

 so far as known, somewhat like its Bridger contemporary. Sinopa, how- 

 ever, is a survivor of an old phylum ; it is an alert and widespread animal 

 distributed from the Rocky Momitain region to northern Africa. 



The affinity, therefore, between America and Europe is only that of 

 descent from similar ancestors; for the time Europe constitutes part of an 

 entirely different iioological region, or Palceardica. 



Geological Succession 



1. Lutetian Stage. — This initial stage (which takes its name from 

 Lutetia, Paris), according to Deperet " exliibits (I) an older fauna of Argenton 

 and Bracklesham, and (II) a newer famia of the calcaire grassier of Paris. 

 In the latter begins the Palceotherium Zone. 



The older fauna marks the beginning of the fissure deposits of Lissieu (2) 

 near Lyons and of Egerkingen (10), Canton Vaud, in Switzerland. The 

 last, rich in the teeth of mammals, has been made famous through the 

 researches of Rlitimeyer,^ who assigned them great geological antiquity. 

 His successor, Stehlin, has properly placed them in the lower portion of the 

 Middle Eocene.* 



To the newer stage belong the rich deposits of La Leviniere (Herault) 

 (7) recently explored by Deperet, yielding perfectly preserved skulls of 

 lophiodonts and horses. 



2. The succeeding Bartonian Stage receives its name from the Barton 

 clays of Hampshire, England. It is sharply defined zoologically as the close 

 of the Lophiodon Zone, including the large fuial stage of lophiodont evolu- 

 tion (L. lautricense) , in which the premolar teeth are complicated, whereas 

 in the L. rhinocerodes of Egerkingen they are simple. With the disappear- 

 ance of these dominant mammals Europe was left during the remainder of 

 the Eocene without any quadrupeds larger than tapirs. The lophiodon 

 Chasmotherium also disappears. The supposed chalicothere Pernatherium, 

 a very aberrant perissodactyl, is first known at this stage. The mammals 

 are other\vise a continuation of those of the Lutetian. Of the same age are 



' Plesiarctomys is probably but not certainly closely related to or identical vnih 

 Paramys. W. D. M. 



^ Deperet, C, L'evolution dcs Mammif^res tertiaires (Eocene). C. R. Acad. Sci. Paris, 

 Vol. CXLI, 1905. 



^ Rlitimeyer, L., Die Eocane Saugethior-Welt von Egerkingen. Ahhandl. schweiz. palaont. 

 Ges., Vol. XVIII, Zurich, 1891. 



* Stehlin, H. G., Die Saugetiere des schweizerischen Eocans, Critischer Catalog der Mate- 

 rialicn, III Teil. Ahhandl. schweiz. palaontol. Ges., Vol. XXXII, Zurich, 190G, pp. 593-595. 



