176 



CIIAKLKS It. ST()('KAi;i» AND A. L. JOHNSON 



Finally, the skulls in this sequence were measured for the 

 sum of the greatest anteroposterior dimensions of the four 

 maxillary premolar teeth (text-fig. 25). Certain specimens 

 in which teeth were missing wore necessarily omitted; this 

 particularly involved the short muzzled bulldog-like skulls 

 which have poorly imbedded teeth. The sums of the antero- 

 posterior widths of the premolars ranged from 56 mm to 

 23 mm, the greatest being to the least as 2.4:1. The sums of 

 the premolars show a general trend of accord with palatal 

 lengths and the other facial measurements, although in detail 

 this resemblance is not very striking. 



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Text-figure 20. Sequence F. Sum of the anteroposterior dimensions of the 

 maxillary premolar teeth. Same skull sequence as text-figure 20. 



Detailed comparisons among the six charts in this sequence, 

 all of which involve measurements of anteroposterior lengths 

 in the facial skeleton, indicate very clearly that the different 

 parts of the face tend to vary in length in a closely comparable 

 manner. It is almost necessarily true that a short muzzled 

 skull will have a short maxilla, a short palate, short premolar 

 region and short nasal bones, though the shortness may not 

 be proportionately the same in the several parts. The only 

 marked deviation from this general harmony in facial skeleton 

 dimensions is found in the lengths of the mandible. Mandibles 

 may be either disproportionately short or long for the as- 

 sociated upper facial skeleton. A prognathism of the upper 

 jaw in some cases or the lower jaw in others may thus result. 



