342 CHARLES R. STOCKARD AND A. L. JOHNSON 



be overcome by well administered bone meal and vitamin D. 

 These hybrid animals are constitutionally defective in their 

 bone and skin reactions, and there is evidence of a defective 

 pituitary-parathyroid complex not yet fully analyzed. 



The head shapes of the F 2 hybrids vary widely, from the 

 long and slender almost dachshund-like head seen in figures 

 3 and 6 in plate 66, to the short muzzled monkey-like face 

 approaching the griffon (pi. 65, figs. 2 and 5). Between these 

 two extremes are various modifications in shapes of the 

 cranium and face. Figures 1 and 4 in plate 65 show a high 

 spherical Brussels griffon-like cranium with a strong depres- 

 sion at the nasion, while the muzzle is slender and somewhat 

 short and the jaws are well developed with normal dental 

 occlusion. As mentioned above, the head of the animal in 

 figures 2 and 5 (pi. 65) is shortened, and the prognathism 

 of the mandible is hidden by the long hair. Figure 6 shows 

 another short face and rounded cranium. The " undershot" 

 prognathism of the lower jaw in this dog is clearly seen in 

 the photograph. 



Plate 66 illustrates three other F 2 Brussels griffon-dachs- 

 hund hybrids. The heads have been photographed in profile 

 at somewhat larger scale and are shown below the picture of 

 the entire animal. The three specimens show evidence of the 

 hypersensitive condition of the skin and there is an infection 

 of mange about the eyelids and other places; the animal in 

 figures 3 and 6 was, in addition, afflicted with rickets. Other 

 puppies living under identical conditions of food and care 

 were not so afflicted, and this is true even of litter mates with 

 different constitutional compositions. 



The short faced condition as expressed in these hybrids 

 differs in several ways from the typical bulldog pattern, 

 particularly in the mandible which is much more shortened. 

 There is also no excessive wrinkling of the skin, as in the 

 bulldog breeds. The mutations giving rise to the flat face in 

 the Brussels griffon have involved factors which influence 

 the growth in length of the mandible much more directly than 



