lyiii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
clear that the result of the comparison of the Miocene and present 
Faune is distinctly in favour of evolution. Indeed I may go further. 
I may say that the hypothesis of evolution explains the facts of 
Miocene, Pliocene, and Recent distribution, and that no other supposi- 
tion even pretends to account for them. It is, indeed, a conceivable 
supposition that every species of Rhinoceros and every species of 
Hyena, in the long succession of forms between the Miocene and 
the present species, was separately constructed out of dust, or out of 
nothing, by supernatural power; but until I receive distinct evi- 
dence of the fact, I refuse to run the risk of insulting any sane man 
by supposing that he seriously holds such a notion. 
Let us now take a step further back in time, and inquire into the 
relations between the Miocene Fauna and its predecessor of the 
Upper Eocene formation. 
Here it is to be regretted that our materials for forming a judg- 
ment are nothing to be compared in point of extent or variety with 
those which are yielded by the Miocene strata. However, what we 
do know of this Upper Eocene Fauna of Europe gives sufficient 
positive information to enable us to draw some tolerably safe infer- 
ences. It has yielded representatives of Insectivora, of Chiroptera, 
of Rodentia, of Carnivora, of artiodactyle and perissodactyle Un- 
gulata, and of opossum-like Marsupials. No Australian type of Mar- 
supial has been discovered in the Upper Eocene strata, nor any Eden- 
tate mammal. The genera (except in the case perhaps of some of 
the Insectivora, Chiroptera, and Rodentia) are different from those 
of the Miocene epoch, but present a remarkable general similarity to 
the Miocene and recent genera. In several cases, as I have already 
shown, it has now been clearly made out that the relation between 
the Eocene and Miocene forms is such that the Eocene form is the 
less specialized ; while its Miocene ally is more so, and the speciali- 
zation reaches its maximum in the recent forms of the same type. 
So far as the Upper Eocene and the Miocene Mammalian Faun 
are comparable, their relations are such as in no way to oppose the 
hypothesis that the older are the progenitors of the more recent 
forms, while, in some cases, they distinctly fayour that hypothesis. 
The period in time and the changes in physical geography repre- 
sented by the nummulitic deposits are undoubtedly very great, 
while the remains of Middle Eocene and Older Eocene Mammals are 
comparatively few. The general facies of the Middle Eocene fauna, 
however, is quite that of the Upper. The Older Eocene pre-num- 
mulitic mammalian Fauna contains Bats, two genera of Carnivora, 
three genera of Ungulata (probably all perissodactyle), and a didel- 
phid Marsupial; all these forms, except perhaps the Bat and the 
Opossum, belong to genera which are not known to occur out of the 
Lower Kocene formation. The Coryphodon, however, appears to 
have been allied to the Miocene and later Tapirs, while Plholophus, 
in its skull and dentition, curiously partakes of both artiodactyle 
and perissodactyle characters; the third trochanter upon its femur, 
and its three-toed hind foot, however, appear definitely to fix its 
position in the latter division. 
