738 PRIMATES 
diameter, and also by the larger size of their external as compared 
with their internal cusps; while the outer border of these teeth is 
placed internally to that of the upper molars. In all these respects 
the teeth of the Chimpanzee make a decided approximation to the 
human type. 
Many young individuals of the Chimpanzee have been brought 
to Europe, but they appear to succumb sooner or later to the effects 
of an unsuitable climate. All these examples show that the dis- 
position of this Ape is gentle, lively, and intelligent, and in all 
respects markedly opposite to that of the Orang. In a wild state 
these Apes are essentially forest-dwellers, and are more arboreal in 
their habits than the Gorilla. They live either in families, or in 
small parties of several families. Frequently at least they construct 
a kind of nest in the trees as a sleeping-place ; the male being said 
to sleep on a forked branch below the level of this nest. In walk- 
ing the Chimpanzee usually supports himself on the backs of his 
closed fingers, and either on the soles of the feet or on the closed 
toes. 
From a distributional point of view the discovery of a fossil 
Ape in the Pliocene of the Punjab, apparently closely allied to the 
Chimpanzee, is of great interest. This determination rests upon 
the evidence of an imperfect palate originally described under the 
name of Palwopithecus, but subsequently referred to the present 
genus. The teeth of this jaw present all the essential characters 
of those of the Chimpanzee, but the two series of cheek-teeth have 
a slight anterior convergence, the premolars are shorter in the 
antero-posterior direction than is usually the case in that species, 
and the outer incisor is relatively narrower than in the latter. In 
these features the extinct 4. sivalensis makes a nearer approxima- 
tion to the human type than is the case with its living congeners. 
Dryopithecus.'—The extinct Dryopithecus of the Middle Miocene 
of France is represented by a single species of the approximate 
size of the Chimpanzee, and appears to be the most generalised 
member of the family. According to the recent observations of 
Professor Gaudry,? while it resembles the Gorilla in that the two 
series of lower cheek-teeth diverge anteriorly and the penultimate 
premolar is larger than the last of that series, it differs in having a 
much longer and narrower mandibular symphysis, and thus indicates 
a transition to the Cercopithecide. A gradual transition in the form 
of the mandible may, indeed, be traced from Dryopithecus, through 
Gorilla, to Anthropopithecus ; the latter having a short and wide 
symphysis, with the two series of cheek-teeth slightly converging 
anteriorly, and the penultimate premolar being not larger than the 
last. In all these specialised characters the jaw of the Chimpanzee 
1 Lartet, Comptes Rendus, vol. xliii. p. 219 (1856). 
2 Mém. Soc. Géol. France, ‘‘ Paleontologie,” vol. i. Mém. No. 1 (1890). 
