THE EVOLUTION OF THE EYEBROW REGION OF THE FOREHEAD. 287 



in his recent paper on " Das Schadelfragment von Briix und verwandte Schadelformen " 

 (10). He takes as a type the condition presented by the frontal bone of the mandrill 

 (Cynocephalus mormon), and he recognises, above the nasion and the margin of the 

 orbital opening, two regions, viz. (l) the superciliary ridge (arcus superciliaris), which 

 extends upwards and outwards from the glabellar swelling (fig. 1, b); and (2) a lateral 

 area situated below and to the outer side of the superciliary ridge. This area he terms 

 the arcus supraorbi talis (fig. 1, d). It stretches from the supraorbital notch to the 



Fig. 2. — The frontal bone of an Alsatian, with strongly marked superciliary eminences (from 

 Schwalbe, " Das Schadelfragment von Briix, etc.," p. 110). 

 a. Fossa supraglabellaris. d. Trigonum supraorbital. 



6. Superciliary eminence. c. Groove between 6 and d. 



external angular process of the frontal bone, and forms a three-sided field between the 

 superciliary ridge above and the margin of the orbital opening below. 



Schwalbe further states that the same parts, in very much the same relationship to 

 each other, may be seen in the eyebrow region of recent man, and he gives outline 

 sketches of the frontal bone of a mandrill and of an Alsatian to illustrate this point. 

 These figures I have taken the liberty to reproduce, so as to make his position on this 

 matter absolutely clear (figs. I and 2). In both of these drawings it can be seen that there 

 is an arcus superciliaris (b) and an arcus supraorbitalis (d), and that these are separated 

 from each other by an oblique furrow, the sulcus supraorbitalis (c), which ascends from 

 the supraorbital notch in an outward and upward direction. 



