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 structure than they have. The Platyrrhines seem to stand at the base of the series. This is another example of the existence of archaic creatures in South America.

'''Fam. 1. Hapalidae.'''—We may begin the account of the Platyrrhine Monkeys with the Hapalidae or Marmosets; for this family is structurally lower than the rest. They have thirty-two teeth, arranged as in the following formula: I 2/2 C 1/1 Pm 3/3 M 2/2 = 32. The molars have three main tubercles, and not four as in the higher forms. The digits are for the most part clawed, not nailed, as in the higher types; the great toe alone bears a flat nail. The tail, too, is ringed, a condition which is characteristic of many of the lower groups of mammals, but not of the higher Apes. The cerebral hemispheres are smooth, but this is a matter rather connected with their small size than with low zoological position. The tails of the Marmosets, unlike those of so many other American Monkeys, are not prehensile though they are long.

The genus Hapale is broadly distinguished from the other genus, Midas, by the fact that the lower incisors slant forwards as in the Lemurs. They are small, soft-furred, long-tailed Monkeys, familiar to every one. There are some seven species, which are entirely restricted in range to Brazil, Bolivia, and Colombia, one species only, H. pygmaea, extending northward into Mexico.

Of Tamarins, genus Midas, there are rather more species—about fourteen. They are South and Central American in distribution. Since both these genera are arboreal in habit, it is extraordinary that they have not the prehensile tails of their American allies. As, however, the late Mr. Bates observed an individual of the species M. nigricollis fall head-foremost from a height of at least 50 feet, alight on its feet, and run off as if nothing in particular had occurred, it is evident that no extra prehensile powers are absolutely necessary. Some of the Tamarins have a long mane; this is well seen in M. rosalia, or rather in M. leoninus, which, if not identical with it, is at least very closely allied to it. The name is obviously derived from the character