WHOLE VOL. SKELETAL REMAINS OF EARLY MAN HRDLICKA bl 



there is on the whole a closer approach to it than in the chimpanzees ; and in 

 one of the skulls seen at the British Museum (Australian, No. io68-<^), as well 

 as in several jaws at the U. S. National Museum, there is a very close approach 

 to the condition such as seen in the Piltdown mandible. 



The anterior border of the ramus is somewhat thicker and duller than it is 

 in an average modern human jaw, especially in that of a cultured white man. 

 It is near to the average border in a chimpanzee; but it is a feature of little 

 diagnostic value, being an expression of strength and not derivation. An equally 

 thick border may be found in some human jaws, while in some chimpanzees as in 

 most modern humans the edge is thinner. 



Internally the upper portion of the ramus shows nothing especially charac- 

 teristic. The impression for the external pterygoid is faint, that for the tem- 

 poralis well marked but of moderate extent. The ridges and depressions, and 

 the location of the mandibular foramen with the hyoid groove, present nothing 

 that is not fairly common in both man and the chimpanzees. 



Taking the ascending ramus as a whole, the conclusion is inevitable that it 

 belonged to an individual in whom all the muscles of mastication (internal 

 pterygoid, masseter, external pterygoid as well as temporal) were of only mod- 

 erate development and activity for a being of the size indicated by the jaw. 

 They were decidedly less than those of actual male chimpanzees, and possibly 

 even a trace less than the average in the females of this form. On the whole 

 the ramus, while bearing some resemblance to that of a chimpanzee in the slight 

 inversion of its posterior border about the angle and the thickness of the anterior 

 border, shows a closer approach to the human type than to that of the chimpanzee. 



The horizontal part or body of the jazv. — The horizontal ramus of the Pilt- 

 down jaw, broken off superiorly in front of the first molar and inferiorly near 

 the symphysis, shows a relatively light structure, comparable much more to a 

 stronger modern human jaw than to that of a chimpanzee. The break shows 

 that the ramus possesses a large cavity (which may have been partly filled by 

 cancellous tissue) that reached without much diminution clear to and evidently 

 through the chin. This condition differs markedly from that of the jaws of chim- 

 panzees, in which the bone is thicker and the internal cavity smaller, particularly 

 at the chin which is filled with sparse and dense cancellous tissue as hard as the 

 compact walls outside of it, and in which the formation by natural means of a 

 similar cavity as seen in the Piltdown specimen seems impossible. This is one 

 more and an important feature, indicating a relatively light use of the jaw, less 

 than in any known chimpanzees. 



The body appears relatively somewhat low, which in man would indicate a 

 female rather than a male individual ; but it could also be a primitive feature. 

 Low bodied jaws are a general feature in the chimpanzees. The vertical height 

 of the body in the Piltdown jaw at the first septum anterior to the first molar, 

 is 3.0 cm.; at the second septum (between first and second molars), 2.9 cm.; 

 and at the third septum (between second and third molars), 3.0 cm. In a series 

 of male chimpanzees in the U. S. National Museum the height at the septum 

 between the second and third molars on the right side measures respectively 

 2.75, 2.8, 2.4, 2.8, 2.65, 2.9, 2.8, 2.85, 2.65, and 2.9 cm. None of the chimpanzee 

 jaws, although most of them are males and larger than the Piltdown specimen, 

 measure even as much as it does in the height of the body. 



