8o SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.83 



The ascending ramus gives the writer the following measurements: Height 

 along the middle to lowest point of notch, 6.1 cm.; ' minimum breadth (allowing 

 for slight damage of the posterior border), 4.25 cm. The angle is close to 112°. 

 These measurements show little that could be regarded as biologically distinctive 

 and could be duplicated in man as well as in some chimpanzees. 



The ramus, finely formed, is of only moderate strength. Both the processes, 

 coronoid and condyloid (the condyle itself is lost), were of about medium human 

 development and quite human in form. This is particularly true of the coronoid, 

 which is sharper and pointing somewhat more forward than it generally is in 

 the chimpanzee. 



The notch between the condyloid and coronoid processes is broad and typi- 

 cally human in form ; in chimpanzees it is as a rule less broad, its posterior por- 

 tion predominates in length and it has lesser inclination than the anterior part. 



Features of special interest are the neck of the condyle and the posterior 

 border of the ramus. The neck of the condyle is rather short and decidedly more 

 slender than it is in chimpanzees, and even in most male modern human jaws. 

 Below the neck the posterior border is rather sharp and towards the angle 

 shows slight inversion rather than eversion, as not seldom in chimpanzees where 

 the internal pterygoid muscles predominate in " pull " over that of the masseter 

 externally ; the same condition may also be met in some humans where the 

 masseters were not well developed. 



That the masseters in the Piltdown specimen were not strongly developed is 

 shown by the smoothness of the outer surface of the angle portion of the jaw 

 which is free of insertion ridges or irregularities. Such a condition is occa- 

 sionally approached in chimpanzees though there are usually plain indications 

 of the attachment of the muscle ; it is clearly approached in some human jaws. 

 The internal pterygoid muscle, attached to the internal surface of the ramus 

 between the mylohyoid groove and the angle of the bone, and serving essentially 

 for protrusion, retraction and in lateral movements of the jaw, in the chimpanzees 

 as a rule predominates in strength and hence in marks of attachment over the 

 masseter, and it does so also in a certain proportion of humans ; but in many 

 humans the extent of the attachment of the pterygoid, even though it may reach 

 the mylohyoid groove is more or less reduced, and in not a few it is the masseter 

 which predominates in strength producing a more or less marked eversion of 

 the lower border of the bone at the angle. In the Piltdown jaw the attachment 

 of the internal pterygoid, while reaching as far as the mylohyoid groove, left 

 only faint traces of its attachments, less even than in many present day human 

 jaws. Nevertheless, the masseter was evidently even weaker, due to which fact 

 the border at the angle is slightly inverted as already mentioned. 



The external surface of the ramus in the Piltdown jaw shows a marked and 

 hitherto unmentioned depression produced by the body of the masseter. The 

 depression begins superiorly just below the condyle and proceeds unevenly 

 forwards and downwards to end in a large shallow concavity over the lower third 

 of the ramus anterior to its middle. Of a similar depression there is found in 

 the grown chimpanzees at most only the anterior portion. In human subjects 

 this fossa is also frequently more or less deficient and irregular ; nevertheless, 



' The condyle, as is well known, is missing ; with the condyle and measured in 

 the usual way (see A. Hrdlicka, Anthropometry, Wistar Inst., Phila., 1921), 

 the height of the ascending ramus would be about 7.0 cm. or slightly over. 



