;io 



CHARLES R. STOCKARD AND A. L. JOHNSON 



skulls differ less in mandibular index than in palatal or 

 upper jaw index, but the F, hybrids range all the way from 

 1 unit above the lowest bassethound index up to the level 

 of the lowest bulldog index. The skulls of the F 2 hybrids 

 fail to reach only the highest values for the bulldogs. In 

 contrast with this, the upper chart shows that the highest 



PALATAL INDEX 



MANDIBULAR INDEX 



Text-figure 67. Bassethound-English bulldog cross. Each vertical line repre- 

 sents an index based on exact measurements of the skull. The series of skulls 

 for palatal indices is the same as used in text-figure 65, and for mandibular 

 indices the same as used in text-figure 66. A, bassethound ; B, English bulldog ; 

 C, F,; D, F 2 ; E, backcross of Fi with bassethound; F, backcross of F, with 

 English bulldog. 



palatal index among twenty-one of the same F 2 skulls falls 

 14 units below the lowest bulldog palatal index. In other 

 words, the skull of the F 2 hybrid may attain the typical 

 bulldog mandibular index far more readily than it can the 

 bulldog upper jaw or palatal index. Although the bulldog 

 lower jaw is longer than the upper, it is not an entirely 

 normal mandible; there is not only some shortening but a 



