234 CHARLES R. STOCKARD AND A. L. JOHNSON 



figure 2 the F x outline is superimposed over the sagittal 

 outline of the dachshund skull, and in figure 3 over the out- 

 line of the Boston terrier skull. The fit with the dachshund 

 skull is closer than that with the Boston terrier skull. The 

 Fj hybrids, as shown in plate 29, resemble in general the 

 dachshund more closely than they do the Boston terrier. As 

 in the dachshund, the legs are short, the tails are long and 

 the ears droop or hang. Although the F l head is larger and 

 less slender than that of the dachshund, it shows even greater 

 deviation from the typical Boston terrier head. The face is 

 shortened and the region of the nasion is decidedly depressed ; 

 the zygomatic arch is more strongly curved than is usual in 

 the long skull, and the lower incisors project beyond the 

 upper, giving a slight degree of undershot jaw. The features 

 of this skull are in many ways a combination of the two 

 parent types. 



These hybrids were vigorously active and normal in be- 

 havior, having advantages in both size and stamina over both 

 the pure stocks. 



Of the eight F t individuals produced, four were breeding 

 bitches, and sixty-five offspring were whelped as a second, 

 Fo, hybrid generation. The living F2 animals exhibited wide 

 differences in size, body form and head type and can be 

 seen in plates 30 (p. 129), 39 and 40. Figures 1 and 2 in 

 plate 39 show litter mate sisters, one with an almost Boston 

 terrier head and the other with an almost dachshund-like 

 head. Photographs of the skulls of these sisters are seen 

 as figures 4 and 5 in plate 36 ; figure 4 approaches the dachs- 

 hund skull somewhat more closely than does the skull of 

 the Fj (fig. 3). The dental occlusion in these F2S is normal, 

 and the teeth are perfectly developed and strong. The zygo- 

 matic arch is not so strongly bowed as in the F! skull, and 

 the nasion is not very deeply depressed. 



Figure 5 in plate 36 is a high, short skull, and some of its 

 features are quite different from either parent stock. The 

 maxilla is short and there is almost complete dental maloc- 

 clusion. The teeth in this skull show an extreme state of 



