508 Mr. J. Wood on Variations in Human Myology. [June 18, 



and 13 females ; i. e. a considerable majority proportionately in the latter 

 sex. In 18 it was found in both arms ; in 5 in the right ; and in 9 in the 

 left only. 



26. Extensor carpi radialis brevior. — In 16 subjects out of the 36 of 

 the present year, the tendon of insertion of this muscle was implanted 

 upon the adjacent part of the base of the second metacarpal, as well as 

 upon that of the third, its normal insertion. In two of these (Nos. 15 & 

 16) this insertion was made by a short but distinct slip. In all the others 

 there was no division of the tendon at its insertion. In the right arm of 

 the females (Nos. 29 & 30) the tendon gave off a slip from its inner side 

 to the origin of the third dorsal interosseous muscle, showing a disposition 

 to the formation of an insertion into the base of the fourth metacarpal, as 

 recorded by Albinus (Hist. Muse. p. 446), and quoted by Macwhinnie. 

 In the Iguana tuberculata^ Mivart describes the single radial extensor as 

 inserted by three tendons into the second, third, and fourth metacarpal 

 bones. Thus, at intervals, there are found in the human arm, slips from 

 the radial extensors to the four outer metacarpals, the extensor ulnaris 

 providing for the fifth. In his paper in the first Number of the * Jour- 

 nal of Anatomy and Physiology ' (Nov. 1866), the author showed the 

 occasional occurrence of a special fiexor also for each of the metacarpals. 



The above insertion of a slip of the brevior into the index-metacarpal is 

 the first indication of that form of intermedins which passes from the 

 brevior to the longior. The latter muscle and tendon, however, seem more 

 prone to this fissuring or differentiation than the former. 



27. Extensor communis digitorum. — In two subjects, abnormalities of 

 this muscle resulted from a division of its muscular belly. In Nos. 5 & 

 13, males, it gave a separate belly to each tendon — as recorded by Albinus, 

 Brugnone, and Meckel. In the female (No. 30) the indicial portion only 

 was provided with a distinct belly, — as mentioned by Henle. In two males 

 (Nos. 7 & 15) and three females (Nos. 24, 33, & 36) there was a multi- 

 plication of its tendons. In the female (No. 24) there were in both arms 

 two tendons to the middle digit. In both arms of the male (No. 15) there 

 were two to the little finger. In the left arm of the male (No. 7) there 

 were two each to the ring- and little digits ; while in the right arm were 

 two each to the index and little fingers, and no less than four to the riiig- 

 digit. In the left arm of the female (No. 36) there were two each to the 

 index, middle, and rm^-fingers ; while in No. 33 there were two each to 

 the middle and ring. On the right hand of the last was a small fusiform 

 muscle, ending in a tendon, which was implanted upon the fascia covering 

 the first interosseous muscle. All these abnormalities find a parallel in 

 those of the extensor longus digitorum pedis. The most noteworthy is 

 the last, which resembles the slip given off" from the tendon in the foot to 

 one of the metatarsals, described in the author's last paper as resembling 

 the formation in the Sloths and some Reptiles. 



In the left arm of a muscular female (No. 27), a large slip of muscle 



