16 Professor Owen, [Feb. 4, 



features that relate to the wielding of the strong jaws and large canines 

 are exaggerated ; the evidence of brain is less ; its proper cavity is 

 more masked by the outgrowth of the strong occipital and otlier 

 cranial ridges. But then the impression so made that the gorilla is 

 less like man, is the same which is derived from comparing a young 

 with an adult chimpanzee, or some small tailless monkey with a full- 

 grown male orang or chimpanzee. Taking the characters that 

 cause that impression at a first inspection of the gorilla, most of the 

 small South American monkeys are more anthropoid ; they have a 

 proportionally larger and more human-shaped cranium, much less pro- 

 minent jaws, with more equable teeth. 



Referring to the diagrams of the skeletons of the adult males of 

 the gorilla, chimpanzee, orang, and gibbon. Professor Owen remarked 

 that the globular cranium of the last, and its superior size compared 

 with the jaws and teeth, seemed to show the gibbons to be more nearly 

 akin to man than any of the larger tailless apes. And this conclusion 

 had been formed by a distinguished French palaeontologist, M. Lartet, 

 and accepted by a high geological authority at home.* The experi- 

 enced Professor of Human Anatomy at Amsterdam had been also cited 

 as supporting this view ; but the lecturer had failed to find any statement 

 of the grounds upon which it was sustained. In the art. Quadrumana 

 of Todd's Cyclopaedia, cited by Lartet,| Professor Vrolik briefly 

 treats of the osteology of the Quadrumana according to their natural 

 families. In " a first genus, Simla proper, or ape,'* he includes the 

 chimpanzee or orang, noticing some of the cliief points by which these 

 apes Approach the nearest to man. He next goes to the second 

 genus, the gibbon (Hylohates)^ notices their ischial callosities, and the 

 nearer approach of their molars, in their rounded form, to the teeth of 

 carnivora than the molars of the genus Simla. Then^ comparing the 

 siamang with other species of Hylobates, Vrolik says, " its skeleton ap- 

 proaches most to that of man," which may be true in comparison with 

 other gibbons, but certainly is not so as respects the higher Slmice. 

 No details are given to illustrate the proposition even in its more 

 limited application ; but the minor length of the arras in the siamang, 

 as compared with Hylobates lar, was probably the obvious character 

 in Vrolik's mind. 



The appearance of superior cerebral development in the siamang 

 and other long-armed apes is due to their small size and the concomi- 

 tant feeble development of their jaws and teeth. The same appear- 

 ance makes the small platyrrhine monkeys of South America equally 

 anthropoid in their facial physiognomy, and much more human-like 

 than are the great orangs and chimpanzees. It is an appearance which 

 depends upon the precocious growth of the brain, as dependent on the 

 law of its development. In all quadrumana the brain has reached 

 its full size before the second set of teeth is acquired, almost before 



* Sir C. Lyell, Supplement to the 5th Edition of a Manual of Elementary 

 Geology, 1859, p. 15. 



t Comptcs Kendus de l'Acad<?mie des Sciences, Juillet 28, 185G. 



