TERTIARY MAMMAL HORIZONS. 13 



this would correspond with Hcptodon, the first of the American 

 LopJiiodoiitidcc. Gaudry ('98, p. 302) parallels with these beds 

 the freshwater Sables Agcicns (d'Epernay), Etagc Agcicn, Le- 

 MOiNE, the mammalian fauna of w'hich has been described by Le- 

 MOiNE as containing LopJiiodon and Pachynoloplins ; but this 

 fauna belongs on a higher level, as in fact Gaudry himself inti- 

 mates. 



The parallel between the Wasatch and the Suessonien of 

 France was first recognized by Marsh in describing Cory- 

 pJiodon. In the meantime vast additions have been made to our 

 knowledge of the Wasatch fauna and practically nothing to that 

 of the Suessonien. Although we know only a fraction of the 

 life of the period, there certainly existed at this time in Europe 

 the successors to certain Cernaysien genera \\hich are repre- 

 sented by descendants in the Upper Eocene. 



The three known genera common to both countries, namely, 

 CorypJiodon, Hyracotlicrunii and Palaoinctis present close struc- 

 tural parallels. 



Filhol records Lop/iiodon lartcti of the Lignites du Soissonais 

 as an ancestor of the true heavy bodied Lophiodontinje, whereas 

 in the Wasatch we find Heptodoii belonging to the light bodied 

 Lophiodonts of the "Helaletes-Colodon " line which subsequently 

 appears in Europe. Platyehavops, mistakenh" compared with 

 Esthonyx by Lydekker has no parallel in America unless 

 among the Arctocyonidoe . Gervais ('59) mentions a rodent-like 

 type of incisor from the Suessonien, but this has not to my 

 knowledge been subsequently described. 



5. Fissure Formations, Egerkingen and Lissieu, younger 

 than the Wasatch 



These formations both represent the remains of animals slowly 

 accumulated in fissures of Jurassic age. The Lissieu fauna is of 

 approximately the same Middle and Upper Eocene duration. 

 As above stated the Egerkingen composite fauna almost cer- 

 tainly does not contain types as old as those of the Wasatch. 

 There is one important exception : the Proviverra typica of Eger- 

 kingen is in the same stage of development as the Siiiopa {Sty- 



