CONNECTING AND MISSING LINKS
have come to a natural end at one time or another, so that we now have but two, or at most three, terminal lines, represented by the true horses, the asses, and the zebras. The lineage of each of these forms is apparently traceable back through millions of years, until the lines ultimately merge.
But it is with the lineage of Man that we are chiefly concerned. Out of some unknown line of primitive mammals arose those small beasts of prey whose lack of prowess necessitated their feeding on such feeble folk as they could overcome—worms, slugs, insects, and small lizards. These beasts are represented in the living fauna by the Insectivora, such as the shrew, the mole, and the hedgehog, which represent ancient lines of descent and display rather conservative forms. As primitive offshoots of this group came on the one hand the stronger feral animals, known as the Carnivora, and a group of tree folk, the Primates. Where the original home of the Primates was we do not know, but we strongly suspect that it was some circumpolar region of salubrious climate where extensive persistently green forests afforded them asylum and an abundance of easily obtainable food. Fossil plants of Eocene age comparable with those living in Cuba today have been found in Greenland and Spitzbergen. It is safe to assume, therefore, that the climate of those lands was then also comparable. From early Eocene time we have a definite fossil record of Primates in England and in Wyoming, some of the American forms being well-nigh identical with the living lemurs or half-apes of Madagascar, an identity implying that these again are persistent types, or "living fossils." In North America these early Primates lingered throughout the Eocene but disappeared there when a change of climate destroyed the tropical forests that had been their home. They migrated through Central America to South America, where their somewhat altered descendants
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