238 Mr. J. Wood on Variations in Human Myology, [June 21, 



17. In three other subjects, besides the two last mentioned, the extensor 

 minitni digiti was found to have a double tendon. In one the muscle also 

 was doubled. 



In subjects 5 and 32 the outermost of the tendons of this double muscle 

 was inserted into the extensor aponeurosis of the ring finger, thus forming 

 a special extensor of this digit (fig. 6 a), joining, before reaching it, with a 

 slip from the common extensor, which directly afterwards again left it, 

 carr3dng some of its fibres to join the little finger. This arrangement was 

 described by the author in his first paper, and has been also noticed by 

 Vesalius, Meckel, and Hallett in Man, and by Church in the Apes. 



18. In this column are found two specimens of that differentiation 

 of the extensor indicts muscle which results in a proper extensor of the 

 middle finger. In fig. 6 (taken from the extensor aspect of the same arm 

 as fig. 3, subject 32) is seen a complete double set of extensor tendons for 

 each of the five digits, in addition to the interesting varieties found on 

 the flexor side (including a whole set of flexors for the five metacarpal 

 bones), and in other parts of the body. It was not found in' the left 

 arm. In subject 13, the extensor medii digiti was found in both arms, and, 

 what is significant, it was associated in both with the flexor carpi ra- 

 dialis hrevis before described, showing a special tendency to development 

 of the muscles of the middle digit. A similar tendency is shown in subject 

 15, by a duplication of the tendon of the indicator, both tendons in this 

 case being inserted into the first digit. 



19. Of the extensor hrevis digitorum manus, described in the author's 

 last papers, fewer examples than usual have been found, none of them 

 very complete. In subject 32 a single slip to the middle finger is found 

 associated with \he proper extensor and a flexor of the metacarpal bone of 

 that digit ; a combination which was present also in the remarkable subject 

 (1) described in the last paper, and, with the exception of the proper ex- 

 tensor, in one other subject last session. It may be taken as a further proof 

 of the specializing tendency in the middle finger in this subject. 



20. Of the inter ossei, five specimens of differentiation are noted, chiefly 

 belonging to the first, or abductor indicis. Two specimens of a palmar 

 interosseus of the thumb are found in Nos. 5 and 32, both presenting 

 numerous other variations. 



21. Among the miscellaneous muscles of the arm the most noteworthy 

 specimen is that of a sternoclavicular muscle, similar to that described by 

 Haller, and more recently by Mr. Berkeley Hill. This muscle (given in 

 fig. 7 c, from subject 27) arises by a thin tendon from the front of the 

 manubrium sterni, just below the origin of the sterno-mastoid. Spreading 

 as a muscular layer upwards and outwards under the clavicular fibres of the 

 pectoralis major (b b', cut and turned up in the figure), it is inserted into 

 the lower border of the clavicle, just in front of the subclavius muscle, 

 from which it is separated by the costo-coracoid membrane (a), extending 

 nearly as far outwards as the origin of the deltoid. 



