570 CHARACTERS OF SIMIIDAE CHAP. 
existing genera, Cebus, Mycetes, and Callithrix, now living in South 
America, are also known in a fossil state. The extinct genus 
Homunculus is known from the Tertiary strata of Patagonia, and 
an apparently allied form is Anthropops. These creatures, how- 
ever, are at present far from exhaustively known. 
Fam. 2. Simiidae.—The Anthropoid, or Man-like Apes, 
may be separated from the lower Apes as a group, Simiae, 
or perhaps better, on account of the after all slender points of 
difference, a family Simiidae, which has the following distinctive 
characters. 
Though arboreal creatures for the most part, these Apes, when 
they come to the ground, progress in at’ least a senii-erect fashion. 
Moreover, when fe as is usualy the case, put their hands 
upon the ground to aid in walking, they do not rest as do the 
lower Apes upon the flat of the hand, but upon the back of the 
fingers. None of the Anthropoids has a tail, or cheek pouches. 
Ischial callosities are only seen in the Gibbons. There is 
‘commonly a laryngeal pouch, which is of large size, and aids in 
the production of the generally loud voice of these creatures. 
The hair is rather more scanty than in the Cercopithecidae, which 
is an approach to Man. The placenta differs in detail from that of 
the lower Apes, and is exactly like that of Man. These Apes show 
as further differences from the underlying Cercopithecidae, the 
greater length of the arms as compared with the legs, and the 
presence of a vermiform appendix to the caecum. In the latter 
but not the former character they agree with Man, whom we 
shall place in a separate family, Hominidae. The Anthropoid Apes 
are entirely Old World and intratropical in range at the present 
time. 
The Gibbons, genus Hylobates, stand quite at the base of the 
series of existing Anthropoid Apes. They are the smallest and 
the most purely tree-frequenting of all the members of that 
eroup. Connected with this habit is the structural peculiarity 
that their arms are proportionately longer than in the other 
Anthropoids. The affinity of the Gibbons to the Catarrhines is 
proved by the presence of distinct but small ischial callosities. 
The arms are so long that when walking upright the hands 
reach the ground. The hallux is well dev eloped. The ribs are 
thirteen pairs. In the skull the chief noteworthy character as 
1 See the books quoted on p. 576 (footnote). 
