126 DISTRIBUTION OF EXTINCT ANIMALS. [PART Il. 
but in some of the species reaching a larger size; Propaleothe- 
rium and Pachynolophus of smaller size and having affinities 
for the other genera named; and Plagiolophus, a small, slender 
animal which Professor Huxley thinks may have been a direct 
ancestor of the horse. In the Lower Eocene we meet with 
Coryphodon, much larger than the tapir, and armed with large 
canine teeth ; Pliolophus, a generalised type, allied to the tapir 
and horse; and Hyracotherium, a small animal from the Lower 
Eocene of England, remotely allied to the tapir. 
Among the Artiodactyla, or even-toed ungulates, the swine 
are represented by several extinct genera, of moderate or small 
size—Acotherium, Cheropotamus, Cebocherus and Dichobune, all 
from the Upper and the last also from the Middle Eocene of 
France ; but Hutelodon, from the phosphate of lime deposits is 
large. The Dichobune was the most generalised type, pre- 
senting the characters of many of the other genera combined, 
and was believed by Dr. Falconer to approach the musk-deer. 
The Cainotherium of the Miocene also occurs here, and an allied 
genus Plesiomeryx from the same deposits as Huteledon. 
The Eocene Anoplotheride were numerous. The Anoplothe- 
rium was a two-toed, long-tailed Pachyderm, ranging from the 
size of a hog to that of an ass; the allied Hurytheriwm was 
four-toed; and there are one or two others of doubtful affinity. 
All are from the Upper Eocene of France and England. 
Rodentia.—Remains referred to the genera Myoxus (dormouse) 
and Sciwrus (squirrel) have been found in the Upper Eocene 
of France; as well as Plesiarctomys, an extinct genus between 
the marmots and squirrels. The Miocene Theridomys is also 
found here. 
Marsupials.—The Didelphys (opossum) of Cuvier, now referred 
to an extinct genus Peratherium, is found in the Upper Eocene 
of France and England. 
General Considerations on the Extinct Mammalian Fauna of 
Europe.—It is a curious fact that no family, and hardly a genus, 
of European mammalia occurs in the Pliocene deposits, without 
extending back also into those of Miocene age. There are, how- 
