556 MARMOSETS CHAP. 
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. 
GRrour LL AT ae aN. 
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: 13 C+ Pm3 M3 = 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, Jidas, 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. pygmaca, extending northward into 
Mexico. 
Of Tamarins, genus J/idas, there are rather more species— 
about fourteen. They are South and Central American in dis- 
tribution. 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 JZ 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 JZ 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 
