300 PROFESSOR D. J. CUNNINGHAM ON 



ing part of the Neanderthal cranium. The eyebrow projections form an almost 

 continuous arch from the glabella to the extremity of the external angular process of 

 the frontal bone ; still, the line of fusion between the superciliary and supraorbital 

 elements is clearly indicated by a faint groove. There is no trigonum supraorbitale. 

 A specimen such as this is very instructive, because it shows that the arched eyebrow 

 elevation (the torus supraorbitalis) distinctive of Type III. is not merely formed by a 

 strengthening of the superciliary eminence and by its fusion with the supraorbital part, 

 but also by a great development of the latter as well. These changes lead to an oblitera- 

 tion of the trigonum supraorbitale — the feature which Schwalbe considers distinctive of 

 all recent skulls. This increased development of the supraorbital element is also evident 

 in the baboon, although the projecting arch-like elevation which it forms is sharply cut 

 off from the superciliary eminence by a pronounced sulcus. The study of the ape skull 

 as well as a large series of human crania thus renders evident the steps by which the three 

 different types of the supraorbital region have been evolved, and more especially do 

 we see the manner in which Type II., which is chiefly characteristic of recent man, 

 may be transformed into Type III., which is distinctive of the gorilla, the chimpanzee, 

 the Neanderthal race, and also of a few exceptional individuals of the present day. 



Supraorbital Region in the Orang and the Gibbon. 



Had our survey been extended over the entire range of the order Primates, it would 

 have been necessary to have recognised other types besides the three which we have 

 stated include all human skulls and the majority of ape skulls. The condition in the 

 orang, for example, is interesting in so far that there is no evidence of the presence of 

 a superciliary element. The supraorbital elements gradually develop into a projecting 

 rim for the upper part of the orbital opening. In the young skull this makes its 

 appearance about the same time as the milk-teeth. At first it is very feebly expressed 

 and separated from the cerebral part of the frontal bone by a narrow groove. Towards 

 the glabella it is extremely narrow, but as it is traced outwards it broadens, and as age 

 advances it becomes more and more projecting and rough, until ultimately in the adult 

 its outer part occupies the whole field of the trigonum supraorbitale. It presents the 

 appearance at this stage as if it were something superadded to the frontal bone, and 

 might be compared to the upper segment of an oval frame attached to the frontal 

 portion of the margin of the orbital opening. Inasmuch as it does not contain a super- 

 ciliary element, it is not a true torus supraorbitalis, and further, it does not take a large 

 share in the formation of the roof of the orbit. 



In certain aged specimens of the orang skull the narrow inner end of this supra- 

 orbital projection may be seen to expand in the glabellar region into a rounded knob- 

 like eminence. Such cases are not common, and they suggest the possibility of this 

 expansion being the representative of a superciliary eminence. I do not think, how- 

 ever, that it can be reckoned as such. 



There are some forms of gibbon in which it is impossible to detect a superciliary 



