Prof. K. A. von Zittel—On the Mammatia. 411 
larthra and Amblypoda shows moreover that the Upper Hocene 
Ungulates had already reached a higher development than those 
immediately preceding them, and this fact is also not less evident 
amongst the Carnivora. The more incomplete Creodontia are, so far 
as wealth of form is concerned, strongly on the decline, even though 
Hyenodon and Pierodon, yet belong to the most numerous and 
strongest Carnivores of that period. Near to these an abundance of 
genuine Fissipede Carnivora make their appearance, which are 
placed with the Canide, Mustelide, and Viverridx, but they yet 
possess so many features in common, that they would certainly 
be united into a single family if they still lived in company with 
their more advanced and variously differentiated descendants of 
the present day. Only the Cats (Pseudelurus, Husmilus) are 
already in the Hocene distinguished by sharply defined characters. 
The Pachylemuride (Adapis, Cenopiihecus, Necrolemur, Micro- 
cherus, etc.) also form a very characteristic element of the Upper 
Hocene fauna; they are connected with Old Tertiary forerunners, 
and combine features of the existing Lemurs and genuine Apes. 
The so-called micro-fauna is fairly abundantly represented by 
Rodents, Insectivora, Bats, and Marsupial Rats (Didelphys). The 
three last-named orders, anyhow, contain species without specially 
noticeable characteristics, so that they could very suitably still have 
existed, and they prove that since the beginning of the Tertiary 
period these groups have made but very little progress. The 
Rodents also form a very conservative element of the Upper Eocene 
group of animals. If in many points of differentiation they are 
behind their successors, they already possess every typical feature 
of the order, and they are hardly more closely connected with the 
representatives of other groups than their still existing descendants. 
Tf we look round for materials for comparison with the Upper 
Kocene mammalia of Europe, it is to North America that we must 
at once again turn our view, where, resting on the richly fossiliferous 
Bridger beds, a filially related but impoverished fauna lies buried in 
the so-called Uinta er Diplacodon beds, in which the Amblypoda and 
Tillodontia have disappeared, the Perissodactyla (Pachynolophus, 
Triplopus, Isectolophus, Diplacodon, Amynodon), the Artiodactyla 
(Protoreodon, Leptotragulus), and the Creodontia (Mesonyx, Miacis), 
claim pre-eminence, and Rodents and Prosimize appear, at least, to 
be indicated by scanty remains. A detailed comparison of the 
contents of the Bridger and Uinta-beds with the Middle and Upper 
Kocene mammals of Europe would certainly yield a variety of 
parallels, but it would at the same time also show that common 
genera or representative members of the same group appear with less 
frequency than in the Older Eocene. Only a few names are re- 
peated in the Huropean and American lists (Didelphys, Hyracotherium, 
Pachynolophus, Nyctitherium, Proviverra), but on deeper search it 
would be found that several Huropean genera turn up again in the 
Western hemisphere in a shallow disguise. Thus, for example, the 
genera Helatetes and Isectolophus take the place of the European 
Lophiodon and Protapirus ; Cadurcotherium is replaced by Amynodon ; 
