57O CHARACTERS OF SIMIIDAE CHAP. 



existing genera, Cebus, Mycetes, and Callitlirix, 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, 1 

 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 semi-erect fashion. 

 Moreover, when they, as is usually 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 

 group. 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 developed. The ribs are 

 thirteen pairs. In the skull the chief noteworthy character as 



1 See the books quoted on p. 576 (footnote). 



