320 CHARLES II. STOCKARU AND A. L. JOHNSON 



An examination of the dorsal views of individual skulls 

 as shown in plate 57 will serve to emphasize the complexity 

 of the reactions we are attempting to analyze. The skull of 

 a highly typed bulldog is shown in figure 5, a typical basset- 

 hound skull is shown in figure 3, and the F 1 bassethound- 

 bulldog hybrid skull is shown in figure 4. This hybrid skull 

 is intermediate in its resemblance to the two parent types. 

 It shows a prognathous condition of the lower jaw as in 

 the bulldog, but the type of the mandible and the position 

 of the projecting incisor and canine teeth resemble more 

 closely these characters in the bassethound. What has actually 

 happened is that the upper facial skeleton has been somewhat 

 shortened while the mandible has not. 



The backcross of this Fj hybrid on the bulldog gave rise 

 to the two skulls in figures 6 and 7. These may be diagnosed, 

 using the bulldog parent for comparison, as bulldog skulls 

 which are too long for perfect type. Each of these skulls is 

 also quite different from the other. 



The backcross of the F x on the bassethound stock produced 

 the two skulls in figures 1 and 2. In general these are closely 

 similar to the pure bassethound skull although, as comparison 

 shows, they are too short for pedigreed type. These two 

 backcross skulls are verv closelv alike. 



PLATE 57 



EXPLANATION OF FIGURES 



Skulls of the hassethound-English bulldog cross shoAving contrast in size and 

 features in the pure breeds ami the resulting condition in the hybrids, particularly 

 flic remarkable size differences to be found among members of the second genera- 

 tion. 



1 Backcross bassethound 1010 $. 



2 Backcross bassethound 1011 $. 



3 Bassethound 277 $. 



4 F, 695 rf. 



5 English bulldog 104 $. 



6 Backcross bulldog 875 g. 



7 Backcross bulldog 876^. 



