THE WASATCH FAUNA. 
271 
2. Divisions found in the Bridger beds, not yet found in the Wasatch: 
Fishes, AmiidcB; Reptiles, Ophidia, Anostira; Mammals, Mesonychiida;, Tillo- 
donta, AcJicenodon, Dinocerata, Palceosyops, most species of Hyrachyus. 
The Wasatch horizon of Wyoming has not yet yielded so many 
species of Vertebrata as those of New Mexico, but the close resemblance of 
the two faunae may be observed in the following list of forms which I 
obtained at several localities: * Fishes, Sihiroids; Mammals, Hyracotherium 
(two species), Phenacodus, Coryphodon (two to three species). As is well 
known, the Wasatch beds underlie those of the Bridger group, and we 
therefore look for their European equivalent in the lower part of the series. 
It has been already pointed outf that the absence of Hyopotamus and Ano- 
plotherium and allied genera from the Bridger horizon precludes an identi¬ 
fication with the Upper Eocene of Europe. The comparison of the Wa¬ 
satch fauna with that of the lowest of the three divisions into which Pro¬ 
fessor Gervais has arranged the European Eocene, shows a remarkably 
close correspondence. This epoch, the Suessonien of D’Orbigny (Orthro- 
cene of Gervais) includes the marls of Rilly and lignites of Soissons, the 
Thanet sands, London clays, etc. Fossils from these beds appear to have 
been no better preserved than those of the Wasatch beds of the Rocky 
Mountains, yet some of the genera are identical, and others closely corre¬ 
spondent, as follows : 
Wasatoh. Suessonien. 
Amhloctonus. PalceonycUs. 
Hyracotherium. Hyracotherium. 
Coryphodon, Coryphodon. 
Diatryma. Gastornis. 
Lepidosteus. Lepidosteus, 
As a point of difference between the beds, there may be mentioned the 
absence of the Tceniodonta from the Suessonien,—a suborder not yet known 
out of North America. Nevertheless, the coincidence between the American 
and European horizons is so close that it may become necessary to include 
them under one name,—that is, if a fuller knowledge of their faunm confirms 
the relations here presented. 
This identification is of much importance to the geology of the North 
* See Eept. U. S. Geol. Sarv. Terrs., 4to, vol. ii, pp. 33-39. 
tAnn. Eept. U. S. Geol. Surv. Terrs., 1873, (1874), p. 462. 
