226 CHARLES R. STOCKARD AND A. L. JOHNSON 



The short headed "pug-nosed" Boston terrier was crossed 

 with the long skulled, long and slender nosed dachshund, and 

 the French bulldog, having a more pronounced bull typed 

 skull, was also crossed with the dachshund. All three breeds 

 are partially dwarfed. The English bulldog, which is of nor- 

 mal size and possesses an extremely shortened skull with 

 prognathous lower jaw, abbreviated muzzle and upturned 

 nose, was crossed with both the German shepherd and the 

 bassethound. The latter two breeds are also of normal size 

 and possess the primitive wolf-typed skull with long, perfect 

 biting jaws. 



The Pekingese has a spherical cranium and almost com- 

 pletely abbreviated facial skeleton, and, although not of typical 

 bulldog pattern, has an extremely achondroplasic skull. We 

 have crossed this dog with the long faced, partially dwarfed 

 dachshund as well as with the normal full sized Saluki, which 

 possesses one of the longest and slenderest of dog skulls. 

 Finally we employed the flat "monkey faced", almost round 

 skulled midget Brussels griffon in crosses with the dachshund. 

 These hybrid matings furnish a wide variety of combinations 

 for head types in association with both the normal sized 

 and dwarfed proportions. 



Without further introduction we may now proceed to sur- 

 vey the head types and conditions which arise in these several 

 hybrid groups. 



THE GENETICS AND EXPRESSION OF SKULL CHARACTERISTICS IN 

 HYBRIDS BETWEEN THE BOSTON TERRIER AND THE DACHSHUND 



This cross has been made in both directions with individuals 

 of each breed serving as sire and as dam in the production 

 of the first hybrid generation. The several matings and the 

 numbers of individuals concerned in the different generations 

 have been previously referred to in connection with the dis- 

 cussion of achondroplasia in the dachshund. Therefore we 

 shall refer only briefly to these facts in the present discussion. 



The measurements and indices of the skull of the Boston 

 terrier and the dachshund are given in table 1, and again 



