I. †TRIGONOLESTIDÆ. _†Trigonolestes_, low. Eoc. II. †LEPTOCHŒRIDÆ. _†Leptochœrus_, low. Oligo. _†Stibarus_, low. Oligo. III. †DICHOBUNIDÆ. _†Homacodon_, mid. Eoc. _†Bunomeryx_, up. Eoc. IV. †ANTHRACOTHERIIDÆ. _†Anthracotherium_, low. Oligo. _†Bothriodon_, do. _†Arretotherium_, do. V. ?†OREODONTIDÆ. † _Protoreodon_, up. Eoc. _†Merycoidodon_, low. Oligo. _†Eporeodon_, up. Oligo. _†Promerycochœrus_, up. Oligo. to up. Mioc._†Merycochœrus_, Mioc. and low. Plioc. _†Pronomotherium_, up. Mioc. _†Mesoreodon_, low. Mioc. _†Merychyus_, low. Mioc. to low. Plioc. _†Leptauchenia_, low. Oligo. to low. Mioc. _†Cyclopidius_, mid. Mioc. VI. †AGRIOCHŒRIDÆ. _†Protagriochœrus_, up. Eoc. _†Agriochœrus_, Oligo. Suborder B. SUINA. Swine-like Animals VII. TAGASSUIDÆ, Peccaries. _†Helohyus_, mid. Eoc. _†Perchœrus_, low. Oligo. _†Thinohyus_, up. Oligo. _†Desmathyus_, low. Mioc. _†Prosthennops_, up. Mioc. and low. Plioc. _†Platygonus_, mid. Plioc. to Pleist. _Tagassu_, Recent, Pleist. in S. A. VIII. †ENTELODONTIDÆ. †Giant Pigs. _†Parahyus_, low. Eoc. _†Achænodon_, mid. and up. Eoc. _†Arcæotherium_, low. Oligo. _†Boöchœrus_, up. Oligo. _†Dinohyus_, low Mioc. Suborder C. TYLOPODA. Camels and Llamas IX. CAMELIDÆ. _†Protylopus_, up. Eoc. _†Eotylopus_, low. Oligo. _†Poëbrotherium_, Oligo. _†Pseudolabis_, low. Oligo. _†Protomeryx_, up. Oligo. and low. Mioc. _†Oxydactylus_, low. Mioc. _†Miolabis_, mid. Mioc. _†Protolabis_, mid. and up. Mioc. _†Alticamelus_, mid. Mioc. to low. Plioc. _†Stenomylus_, low. Mioc. _†Procamelus_, up. Mioc. and low. Plioc. _†Pliauchenia_, up. Mioc. to mid. Plioc. _Camelus_, Pleist. _Lama_, Plioc. to Recent, S. A. X. †HYPERTRAGULIDÆ. _†Leptotragulus_, up. Eoc. _†Leptoreodon_, up. Eoc. _†Leptomeryx_, low. Oligo. _†Hypertragulus_, Oligo. _†Hypisodus_, low. Oligo. _†Protoceras_, low. Oligo. _†Syndyoceras_, low. Mioc. Suborder D. PECORA. True Ruminants XI. CERVIDÆ. Deer. _†Blastomeryx_, low. Mioc. to low. Plioc. _Cervus_, Pleist. and Rec. _Rangifer_, Pleist. and Rec. _Alce_, Pleist. and Rec. _†Cervalces_, Pleist. _Odocoileus_, Pleist. and Rec., N. and S. A. _Mazama_, Pleist. to Rec., S. A. XII. †MERYCODONTIDÆ. †Deer-Antelopes. _†Merycodus_, mid. Mioc. to low. Plioc. _†Capromeryx_, Pleist. XIII. ANTILOCAPRIDÆ. Prong-Bucks. _Antilocapra_, Pleist. and Rec. _?†Dromomeryx_, mid. and up. Mioc. XIV. BOVIDÆ. Antelopes, Sheep, Goats, Oxen, etc. _†Neotragocerus_, _†Ilingoceros_, _†Sphenophalus_, low. Plioc. _†Preptoceras_, _†Euceratherium_, _†Symbos_, Pleist. _Ovibos_, Pleist. and Rec. _Bison_, Pleist. and Rec.