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

—138 DISTRIBUTION OF EXTINCT ANIMALS. [part ii.Mexico : Meniscotherium, having resemblances to Palccosyops,Hyopotamus, and the Limnotheridie ;Phenacodus, the size of ahog, of doubtful position, but perhaps near Motherium ; andAchmnodon, as large as a cow, but more hog-like than the preceding.Another new genus from the Miocene of ColoradoPclonax—issaid by Professor Cope to come between Elotheriurnand Hippopotamus.The Camelidse are very abundant, and form one of the moststriking features of the ancient fauna of America. Procamelus,Homocamelus, and Megalomeryx, are extinct genera found inPliocene formation ; the first very closely allied to the OldWorld camel, the last smaller and more sheep-like. In theMiocene two other generatheoccur, Poebrotherium and Protomeryx,the former allied to both the camel and the llama.Deer are represented by a single species of Ccrvus in thePliocene, while two extinct genera, Leptomeryx and Mcrycodus,are found in the Miocene deposits, the latter indicating a transitionbetween camels and deer. Two other genera, Hypisodusand Hypertracjulus, of very small size, are said by ProfessorCope to be allied to the Tragulidse and to Leptomeryx.The Bovidse, or hollow-horned ruminants, are only representedin the Newer Pliocene by a single species of an extinct genus,Casoryx, said toWe now come toan exclusively American family, the Oreodontidw,which consisted ofbe intermediate between antelopes and deer.small animals termed by Dr. Leidy,"ruminating hogs," and which had some general structuralresemblances to deer and camels. They abounded in NorthAmerica during the Pliocene, and especially during the Mioceneepoch, no less than six genera and twenty species having beendiscovered. Mcrychus contains the Pliocene forms ; whileOreodon, Eporeodon, Merychochcerus, Zeptauchcnia, and Agriochcerusare Miocene. The last genus extends back into theEocene period, and shows affinity to the European AnoplotheridtBof the same epoch.Proboscidea.—The Elephantidse are only represented inAmerica by one species of Mastodon and one of Elephas, inthe Newer Pliocene deposits. In the Older Pliocene, Miocene,