10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



making the entire tooth shorter and more nearly circular in outline 

 than in any of the great apes. The posterior shortening occurs in the 

 region occupied by the talonid and the postero-internal cingulum. 

 The talonid is therefore less constantly present than in the great apes, 

 though it appears to occur normally in n^ (where it is sometimes 

 divided into two cusps), often in m 3 , and less frequently in m 2 ; rarely 

 it is present in all three teeth. The postero-internal cingulum is 

 seldom a noticeable element. The secondary enamel folding though 

 present is less evident than in any of the great apes. In general the 

 lower molars of the Hominidce may be described as like those of Pan 

 but with higher crowns, lower, broader, less sharply-marked-off 

 cusps, less wrinkled enamel, and more rounded-off anterior and 

 posterior borders, the rounding-off behind practically eliminating the 

 postero-internal cingulum and decidedly reducing the talonid or 

 "fifth cusp" (compare pis. 3 and 4). 



Two main facts are now evident : that among the living and recently 

 extinct great apes and Hominidce (a) all the more important features 

 of each group remain constant in such widely separated forms as 

 Homo sapiens and H. heidelbergensis 1 on the one hand and Pongo } 

 Gorilla and Pan on the other, and (b) each known genus is sharply 

 differentiated from all the others by characters visible in the Pilt- 

 down jaw. 



Comparison of the Piltdown Jaw and Teeth With Those of 

 Other Members of the Order 



The Piltdown jaw (pi. 1, fig. 2, and pi. 2, fig. 2) admittedly differs 

 from every known mandible of living or extinct members of the 

 family HominidcB. Although broken away a little to the right of the 

 symphysis, it has an abrupt anterior bend which is exactly that of a 

 great ape. The symphyseal region extends conspicuously behind the 

 level of the incisors. The region of the mylohyal ridge is smoothly 

 rounded. The two molars (pi. 2, fig. 2) show no indication of the 

 beginning of a curve in the toothrow. The main axis of the first tooth 

 is continued backward by that of the second in a line passing as far to 

 inner side of condyle as in the Pongidce. In front of the first molar 

 the entire hinder border of the alveolus of pm 4 is plainly visible. It 

 shows that the missing tooth was fully as large as in the great apes 



1 Regarded as a distinct genus by at least two authors : Bonarelli, Revista 

 Ital. di Paleont., Perugia, vol. 15, p. 26, March 15, 1909 {Paleoanthropus) ; and 

 Ameghino, An. Mus. Nac. de Buenos Aires, vol. 19 (ser. 3, vol. 12), p. 195, 

 July 27, IQ09 (Pseudhomo). 



