178 CHARLES R. STOCKAKD AND A. L. JOHNSON 



only 23 mm or as 2.4:1. The top of this chart forms an almost 

 uniformly regular slope. 



Similar measurements for the mandibular premolar teeth 

 (text-fin. 27) range from 42 mm down to only 16 mm, or 

 as 2.(5:1. The range in size is about the same for both series, 

 but the mandibular premolars are definitely smaller in all 

 typed jaws. The largest total mandibular premolar dimen- 

 sions are only three-fourths as much as the greatest total 

 maxillary premolar dimensions, and the sum of the smallest 

 maxillary premolars is one and one-half times greater than 

 the smallest mandibular total. 



3o 



/o 



Text-figure '21. Sequence G. Sum of the anteroposterior dimensions of the 

 mandibular premolar teeth. Same skull sequence as text-figure 26. 



A comparison of text-figures 26 and 27 shows that there 

 is a fail- general accord in total widths of premolar teeth 

 in the upper and lower jaws. However, great individual 

 deviations are indicated. For example, the fifth skull in the 

 series totals 53 mm for the maxillary premolar teeth against 

 only 34 mm for the mandibular; and in the tenth skull this 

 relation is 50 mm against 27 mm, the sum of the antero- 

 posterior dimensions of maxillary teeth being nearly twice 

 that of the mandibular teeth. These facts, along with other 

 knowledge of the teeth which we shall present, indicate that 

 in these highly modified dog skulls the size of the teeth is 

 quite independent of the size of the jaw 



