THE CHIMPANZEES AND ORANGS. 77 



squamosal (27) and parietal (7) is even and is slightly concave upwards instead of being 

 convex as in Man; that between the mastoid (s) and parietal (7) is convex upwards 

 and is continued backwards upon the lambdoidal crista, where it bends down to define 

 the mastoid from the superoccipital. The coronal suture (27, 11) becomes obliterated 

 at the base of the fronto-parietal crest (n, 7, s) at the junction of its middle and anterior 

 thirds, thus indicating the proportion of that crest which is formed by the coalesced 

 frontal bones. 



The remarkable skull above- described and compared belongs to the ' Philosophical 

 Institution of Bristol,' and I am indebted to the liberality of the Council of that Insti- 

 tution not only for the opportunity of describing it, but likewise for the permission to 

 make such a section of the skull as would best display the relative proportions of the 

 cranium and face. 



Permission to make a similar section of the skull of an adult male Orang (Simia 

 Satyrus) in the Museum of the Zoological Society having been granted with a like en- 

 lightened desire for the advancement of knowledge, by the Council of that body, I next 

 proceed to lay before the Society the results of the comparisons of these sections with 

 each other and with similar sections of the skulls of different races of the Human species. 



In the comparison of the Human skeleton with that of other mammalia, especially 

 those of the quadrumanous order, the most striking and characteristic differences are 

 presented by the skull, and depend chiefly upon the different proportions between the 

 cranium and the face, i. e. between the part lodging the brain and that forming the 

 cavities for the eyes, the nose and the mouth. 



These differences have been indicated in a readily appreciable manner by the angle 

 which a line drawn from the most prominent part of the forehead to that of the upper 

 jaw forms with a second line extended from the lower border of the external auditory 

 canal to the lower border of the bony nostril (PI. XXVIII. C . . . . C) '. But this angle, 

 called by Camper the facial angle, fails, as Cuvier^, Mr. Lawrence^ and others have well 

 remarked, to indicate precisely the relative size of the brain-case to the jaws : it is 

 affected of course by whatever may occasion a prominence of the outer wall of the 

 glabella or frontal part of the skull, and this may be occasioned either by the pro- 

 duction of a strong superorbital ridge, or by the interposition of large sinuses between 

 the two tables of that part of the skull, or by both circumstances. 



The difference between the Orang {Pithecus, PI. XXIX.) and Chimpanzee {Troglo- 

 dytes, PI. XXVIII.) in the development of the superorbital ridge (n) affects materially 

 the facial angle, whether taken after the Camperian, the palato-faciaP (B B), or the 



' Camper, as defined by Cuvier, Lemons d'Anat. Comp. torn. ii. (Ed. 1799), p. 5. ' Ibid. p. 9. 



' Lectures on Man, 8vo, 1819, p. 171. 

 In this method, proposed by Dr. Barclay, the horizontal line is drawn parallel with the under surface of 

 the bony palate. But the plane of the palate varies much in the mammalian series in its relation to the base 

 of the cranium. 



n2 



