108 CHARLES R. STOCKARD 



ward rotation of the carpal component of the wrist is partly 

 blocked by the moderately long distal process of the ulna, 

 and consequently the F! bassethound-Saluki shows only a 

 slight lateral bend at the wrist and mild abduction of the 

 front foot, as may be seen from life in plate 11 (fig. 1). The 

 foot skeleton in the F! is intermediate when compared with 

 those of the Saluki and bassethound. 



The leg skeleton from the F x bassethonnd-shepherd hybrid 

 (second in fig. 2) is of a pronounced achondroplasic type. 

 The scapula is wide and the humerus short, thickened and 

 decidedly twisted on its long axis. The radius and ulna are 

 much deformed. Unfortunately the photograph does not 

 clearly indicate that the distal end of the ulna extends only 

 a little below the end of the radius and does not therefore 

 entirely prevent lateral rotation and some abduction of the 

 front foot. The F! bassethound-shepherd leg may permit a 

 wider degree of abduction of the foot than does the basset- 

 hound-Saluki leg. 



Finally, the F x bassethound-bulldog leg skeleton (third in 

 fig. 2) could pass for the fully expressed achondroplasic type. 

 The scapula is very nearly the same as in the bassethound. 

 The humerus is also much the same, but the radius and ulna 

 are not quite so severely bent. The distal process of the 

 ulna falls entirely short of the end of the radius so that the 

 foot of the F! bassethound-bulldog is twisted and abducted 

 about as fully as would be found for the pure bassethound. 

 This is illustrated clearly from living specimens in plate 

 19 (p. 97). 



The three Fj leg skeletons in figure 2 of plate 23 show 7 that 

 the single factor for achondroplasic leg growth produces 

 different degrees of this deformity in different breed com- 

 binations. These three specimens are heterozygous for the 

 achondroplasic factor which we have designated as s. They 

 carry as the allelomorph of this gene the factor I for normal 

 growth in length. However, the three Fj leg skeletons in- 

 dicate that the I factor is not in all cases equally strong in 

 counteracting the effect of the s, or a more likely possibility 



