230 CHARLES E. STOCKABD AND A. L. JOHNSON 



bite of the dog. The four upper and lower premolar teeth 

 are set with abundant space and without occlusal contact, 

 which is a normal arrangement and provides for the holding 

 and carrying of objects in an almost non-biting region of 

 the mouth. As is well known, a dog may handle delicate and 

 breakable articles and carry them without damage for long- 

 distances. When changing the nest, the bitch frequently 

 carries the tender young puppies in her mouth without injury 

 to or complaint from the puppies. Further, this premolar 

 interval with no occlusal contact enables the dog to hold 

 and carry an object with a minimum of muscular effort. The 

 molar teeth of the dachshund skull show a well adapted 

 occlusion. These form the jaws' strongest pulling and crush- 

 ing arrangement. In taking hold to tear and chew the food 

 from a carcass, the dog opens his jaws wide and twists his 

 head far to one side in order to secure a strong grip on 

 the tough tissues with the molar teeth. As the photograph 

 clearly shows, the dachshund's jaws are properly formed to 

 function in these several ways. 



Figure 2 in plate 36 illustrates the Boston terrier skull. 

 This skull as a whole is high and short when compared with 

 that of the dachshund. The cranium approaches a spherical 

 shape and is smooth dorsally, with no sagittal crest and only 

 a feebly expressed occipital spine. The frontal region is 

 strongly arched, giving prominence to the forehead and 

 exaggerating the depression at the nasion. The zygomatic 

 arch is short and strongly curved, making the skull wider 

 than it is long; this is clearly seen in figure 4 of plate 38. 

 The jaws in this dog are much shortened and are poorly 



PLAT J] 37 



EXPLANATION OF FIGURES 



Mandibles of the cross between the dachshund and Boston terrier showing 

 contrasting characteristics of the pure breeds and the resulting conditions in 

 the first and second generation hybrids. 



1 Dachshund 255 $. 4 F, 294 ?. 



2 Boston terrier 7(i $. 5 F, 296 $. 



3 Fj 130 $. (i F, 295 $. 



