THE EVOLUTION OF THE EYEBROW REGION OF THE FOREHEAD. 



289 



become fused together so as to produce the striking arcuate elevation which distinguishes 

 the eyebrow region in this cranium. Further, the term, torus supraorbitalis, which 

 Schwalbe suggests should be applied to it appears to me to be both useful and 

 appropriate. Indeed, I only take exception to the assertion that, while in the Neander- 

 thal cranium the two elements, the arcus superciliaris and the trigonum supraorbital, 

 run together and become fused into one continuous arch, these elements invariably 

 remain separate in the crania of recent man. 



Fig. 4. — Outline tracing of the frontal region of a French skull. 

 b. Arcus superciliaris. d. Trigonum supraorbitale. 



In studying the eyebrow region in man and the ape it will be convenient to look 

 upon the elements which are typically present as being three in number. These 

 elements are represented by the following parts : — 



1. The supraorbital margin or the frontal part of the rim of the orbital opening. 



2. The superciliary arch or ridge. 



3. The trigonum supraorbitale. 



According to the manner in which these three elements are arranged with reference to 

 each other, three types of the supraorbital region may be distinguished. 



At the same time, however, it should be recognised that the three elements are not 

 always present, either separate and distinct from each other, or in combination with each 



