GENETIC TYPE AND THE ENDOCMNES 



239 



given similar results, and this phenomenon also occurs in 

 hybrids from crosses of other long and short jawed breeds. 



Attention may be called to the fact that the Boston terrier 

 is bred for the white on its chest and chin, as shown in 

 plates 29 (fig. 2) and 43 (fig. 1) (pp. 127 and 245). The dachs- 

 hunds, as seen in the same plates, never show such markings. 

 In the hybrids from this cross, the short Boston terrier-like 

 lower jaw has the white markings underneath, and the chests 

 are also white, as plate 40 indicates. The appearance of 

 these animals suggests that the anterior ventral region is 

 Boston terrier in constitutional type while the rest of the 

 head and the body clearly resembles the dachshund. 



A fair impression of the general range in type of the hybrid 

 skulls may be obtained by again referring to plates 36 and 

 37 and text-figure 56. Plate 36 shows the entire skulls, and 



294 f, 



Text-figure 56. Sagittal outlines based upon exact measurements of the skulls 

 of the Boston terrier and dachshund, and of the first and second generation 

 hybrids from this cross. (1) 84$ dachshund and 76$ Boston terrier; (2) 84$ 

 dachshund and 130 $ F 1 ; (3) 76 <j> Boston terrier and 130 $ F,; (4) 84 $ dachshund 

 and 294 $ F 2 ; (5) 76 $ Boston terrier and 295 $ F 2 ; (6) 295 $ F 2 and 294 $ F 2 . 



