The geographical distribution of animals, with a study of the relations ...

126 DISTRIBUTION OF EXTINCT ANIMALS. [part ii.but in some of the species reaching a larger size ; Propalaiotheriumand Pachynolophus of smaller size and having affinitiesfor the other genera named ; and Plagiolopfius, a small, slenderanimal which Professor Huxley thinks may have been a directancestor of the horse. In the Lower Eocene we meet withCoryphodon, much larger than the tapir,and armed with largecanine teeth ; Pliohphus, a generalised type, allied to the tapirand horse ; and Hyracotherium, a small animal from the LowerEocene of England, remotely allied to the tapir.Among the Artiodactyla, or even-toed ungulates, the swineare represented by several extinct genera, of moderate or smalls ize— Acotherium,Chceropotamus, Cebochmrus and Dichobune, allfrom the Upper and the last also from the Middle Eocene ofFrance ; but Eutelodon, from the phosphate of lime deposits islarge. The Dichobune was the most generalised type, presentingthe 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 alliedgenus Plesiom&ryx from the same deposits as Euteledon.The Eocene Anoplotheridae were numerous. The Anoplotheriumwas a two-toed, long-tailed Pachyderm, ranging from thesize of a hog to that of an ass ; the allied Eurytherium wasfour-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 Eoceneof France ; as well as Plesiarctomys, an extinct genus betweenthe marmots and squirrels. The Miocene Theridomys is alsofound here.Marsupials.—The Didclphys (opossum) of Cuvier, now referredto an extinct genus Peratherium, isof France and England.found in the Upper EoceneGeneral Considerations on the Extinct Mammalian Fauna ofEurope.— It is a curious fact that no family, and hardly a genus,of European mammalia occurs in the Pliocene deposits, withoutextending back also into those of Miocene age.There are, how-