286 SCIENCE PROGRESS 



apes, but they are sufficient to prove that the Simiidae were 

 virtually fully evolved by the Middle Miocene. 



And when we pass to the gibbonoid group we find, as we 

 should expect, that they are still 'more ancient animals. All 

 the living gibbons are of course usually included in one genus, 

 Hylobates. This same genus dates from the Miocene. Various 

 jaws and teeth have been recovered from the Miocene and 

 Pliocene of France, Switzerland, and Austria; and although the 

 first specimen, which was discovered more than sixty years 

 ago, was placed in a new genus, Pliopithecus, most writers agree 

 now that the distinctions are too slight to justify a separation 

 from Hylobates. There are, however, several fossil species, of 

 which the best known is H. antiquus. 



This is all that was known of the extinct gibbons until very 

 recently. Hylobates could be traced back along with the greater 

 apes to the Middle Miocene, but no farther. It was clear, 

 however, that the primitive gibbonoid stock must be older than 

 the great apes ; it was to be inferred that primitive apes existed 

 at least as far back as the Lower Miocene. And that such an 

 inference would have been sound is now triumphantly demon- 

 strated by the discovery of the two rami 1 of a small ape's jaw 

 in the Oligocene of Fayum, Egypt. The two rami were broken 

 away from each other by a fracture across the region of the 

 symphysis, and all the incisors and one canine are missing, but 

 the two halves clearly belong to the same jaw. The specimen 

 has been described in great detail by Prof. Max Schlosser, 2 of 

 Munich, the leading German authority on fossil apes. The jaw 

 is closely similar to those of the so-called Pliopithecus, and hence 

 the animal has been named Propliopithecus by Schlosser, a name 

 which unfortunately becomes meaningless if we no longer retain 

 the title Pliopithecus for the Miocene gibbons. 



Propliopithecus chiefly differs from Hylobates in having 

 extremely small canine teeth, which give the dentition a 

 fortuitous resemblance to that of man. Schlosser hazarded the 

 suggestion that the genus may be the common ancestor of all 

 the Hominidae and all the Simiidae. Without making that 



1 In the paper already referred to, Sutcliffe erroneously states that only one 

 ramus was found. 



* See " Beitrage ziir Palaontologie und Geologie Oesterreich-Ungarns und des 

 Orients, Mitteilungen des Geologischeti und Palaontologischen Institutes der Uni- 

 versitat IVien. Bandxxiv. Heft n, p. 52. 



