136 L W. G. Bilchner: 



the length of the palate, and secondly, the size of the nasopharynx, 

 which may be estimated by the distance from the pharyngeal tubercle 

 and basi-occipital to the palatal spine, and thirdly, the degree to 

 which the base is bent at the sphenoethmoidal junction. 



Keith (5) has also devoted some thought to this problem, and in 

 an extract from "Nature," he states: — "The prognathism of the 

 negro is due to several factors; it is chiefly due not so uuich to a 

 larger, but a healthieir dental development, which ensures a due for- 

 ward revolution of the jaws during the eruption of the permanent 

 teeth, thus providing an ample air-way through the pharynx. In 

 Europeans the revolution forwards of the jaAvs showed a distinct 

 tendency to become arrested preniiaturely, thus contracting the 

 pharynx. The negro condition was the more simian, but it also 

 one which modern Europeans would willingly share -with hin), because 

 of its functional methods." 



The correlation between prognathism and other cranial features 

 has also been exhaustively studied. Thus Thomson (6) says that an 

 association between dolichocephaly and prognathism has been widely 

 recognised, and he himself finds that prognathism is generally cor- 

 related with an extension backwards of the occipital region, a view 

 Dati'ner (7) also holds. Brinton (8) considers this correlation be^ 

 tween prognathism and dolichocephaly is brought about by increased 

 muscular action. But, whatever the cause of such association of 

 prognathism and dolichocephaly uDay be, F'lower (9), Wohlbold (10) 

 and Duckworth (11) are each clearly of opinion that it is, as exem- 

 plified in the case of the Australian aboriginal, a. characteristic of 

 race. 



Huxley (12) was of opinion that there existed a relationship l>etwet^n 

 prognathism and the slope of the foram.en occipitale magnum. The 

 greater the facial skeleton, that is, the more pronounced the degi-ee of 

 prognathism, the more perpendicular was the slope of tlie foramen 

 occipitale magnum found to' be. By superposing median diagrams of 

 the highly prognathic skulls of a negro, Australian and Tartar, be 

 found that the slope of the foramen occipitale magnum in these 

 particular sculls formed a somewhat smaller angle with the basi- 

 cauial axis, than was the case in orthognatic skulls. On the other 

 hand, Welcker (13) failed to see any connection between prognathism 

 and the slo})e of the foramen occiptile magnum, but thought there 

 was some correlation between prognathism and the position of the 

 opening, which, as Bolk (1-i) says, " comes practically to the same 

 thing, if a connection between position and slope be assumed.' 

 Welcker (15) says, " Biegt am Vordersiliadd der Oberkiefer des 

 Menschen mehr nach vorn (Prognathismus) so riickt /ugleich am Hin- 

 tersc'hadel das Foramen medullare mehr nach riickwarts." Aeby's (IG) 



