126 DISTRIBUTION OF EXTINCT ANIMALS. [part ii. 



but in some of the species reacliintr a larger size ; Propalmotlie- 

 rium. and Pachynoluplms 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 

 Corypliodon, 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 — Acotherimn, Chceropotamus, Cchochcenis and Dichohiuie, all 

 from the L^pper and the last also from the Middle Eocene of 

 Erance ; but Uatelodon, from the phosphate of lime deposits is 

 large. The Dichohime was the most generalised type, pre- 

 senting the characters of many of the other genera combined, 

 and was believed by Dr. Ealconer to approach the musk-deer. 

 The Cainotherium of the Miocene also occurs here, and an allied 

 genus Plcsiomeryx from the same deposits as EiUeledon. 



The Eocene Anoplotheridai were numerous. The Anoplotlie- 

 rium was a two-toed, long-tailed Pachyderm, ranging from the 

 size of a hog to that of an ass ; the allied Eurytheriuin was 

 four-toed ; and there are one or two others of doubtful affinity. 

 All are from the Upper Eocene of France and England. 



Rodentia. — Eemains referred to the genera Myoxus (dormouse) 

 and Sciurus (squirrel) have been found in the Upper Eocene 

 of Erance ; 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 Considei'ations 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- 



