The indigenous land mammals of the West Indies consist of three groups: (1) Insectivora, (2) hystricomorph rodents, (3) gravigrade edentates. No perissodactyls (horses, rhinoceroses, tapirs, etcetera), no artiodactyls (peccaries, deer, antelopes, etcetera), no proboscideans (elephants, mastodons, etcetera), no true carnivores (dogs, cats, raccoons, mustelines, bears, etcetera). Nor are there any sciuromorph, lagomorph, or myomorph rodents, shrews, moles, hedgehogs, or opossums. All these large groups, most of them abundant and varied in Tertiary North America, are wholly absent. Nor do the Insectivora, rodents, or edentates include anything at all nearly allied to any North American members of the order or derivable from anything known to have inhabited North America in the later Tertiary.
Most of these North American groups invaded South America in the Pliocene and are part of its later fauna. In the Miocene and early Tertiary they are not found in South America, but their place is taken by . . .