132 CHARLES E. STOCKARD 



the second with its slenderer Boston terrier-like quality of 

 bone. The scapula in each of these limbs is long and narrow 

 and the humerus, as well as the radius and ulna, is long 

 and normally shaped. The distal epiphysis of the ulna extends 

 well below the end of the radius and prevents lateral rotation 

 and abnormal abduction of the foot. 



The foot in the first skeleton, from 1696 S , shows a very 

 rare abnormality. The fourth metacarpal bone is abnormally 

 short, only about half normal length, and the proximal phalanx 

 of the fifth toe is raised into the position that should be 

 occupied by the distal half of the metacarpal. The middle 

 phalanx of the toe is reduced to a knob and fused with the 

 ungual segment. This is clearly an abnormality occurring 

 in a normal long leg and having no connection with our 

 present subject. Had it arisen in a short achondroplasia leg 

 it might have been suspected of association with the other 

 skeletal deficiencies. 



The third skeleton from this litter illustrates the incom- 

 plete short si condition. The scapula, which is short and 

 broad in shape, has a higher index of width to length than 

 in the two long skeletons. The anterior border changes di- 

 rection with a sharper angle as the articular end of the 

 scapula is approached, giving a rectangular rather than an 

 ovoid outline to the shoulder blade. This tendency is fre- 

 quently seen in the achondroplasia limbs of the other crosses. 

 The humerus is shortened and characteristically twisted in 

 shape. The radius and ulna are short, allowing excessive 

 lateral rotation and abduction at the wrist joint. 



The four right front leg skeletons in figure 2 of plate 32 

 are from another litter of F 2 dachshund-Boston terrier hy- 

 brids. The first skeleton in this group is long and of rather 

 Boston terrier bone type and the other three are classed as 

 intermediate, si, for short. The same differences between 

 shapes of scapula and length and form of humerus, radius 

 and ulna noted in the first group are again found here. The 

 foot in the long leg has the normal straight-to-the-front 

 position while the other three feet are rotated laterally and 



