222 CHARLES R STOCKARD AND A. L. JOHNSON 



have a very low index, ranging from 23 to 43, while the long 

 skulls range from 97 to 117. The range within each type is 

 only 20, while the difference between the highest index of 

 one type and the lowest of the other is 54, or 2.7 times 

 greater than the range within the types. 



The breadth-height indices (distance from auditory meatus 

 to bregma divided by the greatest cranial width) show an 

 overlapping in the curves for the two types and are clearly 

 of no significant value in type differentiation. 



The proportion of palate to total skull base, as well as 

 the proportion of palatal process from the palate bone to 

 the total palate, is seen to differ only slightly among the 

 breeds. It will be recalled, however, that the series of seventy 

 skulls of various breeds gave clear indication of the sig- 

 nificance of these palatal proportions, and we are quite certain 

 that these proportions are valuable for type differentiation 

 in spite of the only slight differences shown in this graph. 



The distances from the rim of the orbit to the infraorbital 

 foramen and from the rim of the orbit to the anterior superior 

 incisal alveolus differ only slightly in the two types of skulls. 

 Any variations in these two measurements are definitely 

 linked ; either both are short or both are long and the relation 

 of one to the other does not change. 



The relation of total anteroposterior dimensions of the 

 maxillary premolars to length of the maxillary premolar 

 region differs in the two types. In the long skulls the pre- 

 molar region is definitely longer than the sum of the widths 

 of the premolar teeth, while in the short skulls the teeth 

 have a greater total extent than does the premolar region. 

 The latter condition causes the teeth to be crowded out of 

 position. The curves for this characteristic indicate that 

 these differences in premolar arrangement are of significant 

 value for separation of the skull types. 



Similar relations between size of the mandibular premolar 

 teeth and premolar regions are not so significant for differ- 

 entiation of types. At this point there is an overlapping of 



