306 CHARLES R. STOCKARD AND A. L. JOHNSON 



Referring again to table 1 of measurements for pure breed 

 dog skulls, we find that certain of these, such as the German 

 shepherd, great Dane and St. Bernard, do have low cranial 

 indices clearly distinguishing them from the small round 

 cranial types, the Boston terrier, French bulldog and the 

 still more brachycephalic Pekingese dog and Brussels griffon. 

 The bassethound, English bulldog and dachshund fall between 

 these extremes, and their cranial indices are therefore not 

 so strongly contrasted with one another. 



The total skull index is a much more highly significant 

 character for contrasting the bassethound and the bulldog 

 skulls than is the cranial index. The lower chart in text- 

 figure 65 represents the skull indices for the same series of 

 bulldog-bassethound skulls as were shown above for the 

 cranial index. The three long bassethound skulls have about 

 equally low skull indices, 59 to 62, while the short wide 

 bulldog skulls have high indices, varying from 96 to 115. 

 Six of the eight bulldog skulls are over 100 in skull index, 

 which means that the zygomatic widths are greater than the 

 lengths of the total skull base from foramen magnum to 

 anterior incisor alveolus. There can be no question of the 

 differential value of this index in the bulldog and bassethound. 



The three Fj hybrid skulls range from 71 to 77 for total 

 skull index, which places them for this width to length rela- 

 tion nearer the value for the skull of the bassethound than 

 for that of the bulldog. The twenty-one skulls from F 2 hybrids 

 range from 66, slightly above the bassethound index, to 89, 

 which is 7 units below the lowest bulldog index. The majority 

 of these skulls have an index close to the F t range. This 

 would indicate that the genetics of the skull index involves 

 much more than a single or simple factor and depends upon 

 a number of factors influencing the growth of various parts. 

 Among the twenty F 2 individuals not one received in its 

 inheritance the entire complex necessary to give a completely 

 short and wide bulldog skull. 



