1868.] Mr. J. Wood on Variations in Human Myology. 511 



In 7 of these, both the tendons were inserted only into the metacarpal. In 

 14, the supernumerary one was inserted into the trapezium also. In 8 of 

 them, shps were given also to the origin of the opponens pollicis ; in 3, to 

 that of the abductor ; and in 4, to both these muscles. In two instances 

 only, the second tendon joined the opponens or abductor without being 

 connected with the trapezium — much resembling the slip of the exten- 

 sor carpi radialis accessorius before described, by producing a digastric 

 abductor of the thumb. The latter has apparently been confounded by ana- 

 tomists with the abnormality under description. In the Orang-outang, the 

 author found the extensor ossis metacarpi pollicis provided with a double 

 tendon, one implanted into the trapezium and giving origin to the oppo- 

 nens pollicis. In most of the lower species of Monkey and Mammalia its 

 tendon is single ; its differentiation is therefore an evidence of elevation 

 of type. 



31. Extensor primi internodii pollicis. — In six cases the belly of this 

 muscle was blended indistinguishably with that of the extensor ossis me- 

 tacarpi pollicis. From this sprang three or more tendons, one of which 

 was inserted into the base of the first phalanx of the thumb. Three were 

 in males, and three in females. Three were in both arms ; two in the right 

 and one in the left only. This arrangement has been found in 4 out of 

 40 males, and in 4 out of 30 females. 



In 5 males, 1 in both arms, 2 in the right and 2 in the left only, the 

 tendon of this muscle was inserted entirely into the ungual phalanx^ 

 either in conjunction with or by the side of that of the extensor secundi. 



In 3 males and 2 females the tendon, though having chiefly its 

 normal insertion, sent forwards a slip to the same destination. This 

 last arrangement has been found in 12 subjects out of 70. 



In the male (No. 7) there were two slips of tendons to this muscle 

 in the right and three in the left arm ; of which two on one side, and one 

 on the other, passed forward to join that of the extensor secundi. 



In three subjects both muscle and tendon were entirely wanting — in 

 the female (No. 19) in both arms, in the female (No. 22) and in the 

 male (No. 14) in the left arm only. Also in the left arm of the female 

 (No. 30) the tendon only (apparently from abortive development) was 

 represented by a slip reaching from the styloid process of the radius to 

 the base of the first phalanx of the thumb, exactly as recorded in a subject 

 in the author's last paper. On the right arm of the same subject the 

 tendon was very feeble, and came entirely from among those of the 

 extensor ossis metacarpi pollicis. The muscle and tendon have been 

 found entirely, or almost wholly wanting in 2 out of 68 males, and in 3 

 out of 34 females, a proportion in the latter sex of three times as many as 

 in the former. 



32. Extensor secundi internodii pollicis. — In 4 females and 6 females 

 the tendon of this muscle was double, both having the normal insertion. 

 In 2 males and 2 females it was so found in both arms, in ] male and 3 



