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



to an inter osseus volaris, the other becoming connected with the ori- 

 gins of the abductor indicis and deep head of the jlexor brevis pol- 

 licis. . On the opposite arm of the same subject, the longior had simply 

 a double tendon, each part of which was inserted into the base of the 

 index-metacarpal, one crossing under the other in a curious way. In the 

 left arm of No. 15, and in both arms of No. 17 also, the tendon of the 

 longior gave off a slip to the pollex-metacarpal. The female (No. 27) 

 had a similar slip in the left arm, and No. 29 in the right arm. Tn the 

 opposite arm of the former was a complicated arrangement of the extensor 

 intermedins . 



The foregoing accessory slips of the extensor carpi radialis longior 

 would not be observed in a casual dissection of the part, the normal 

 and abnormal parts of the tendon being closely applied to each other and 

 divided by a mere chink. It is only by following closely the tendons to 

 their ultimate insertion, and removing the dorsal interosseous fascia where 

 it covers and conceals them, that the real insertion becomes apparent. 

 Hence it appears that this abnormal slip, though now found to be not in- 

 frequently present, has never before been recorded. Macwhinnie mentions 

 that the tendon of the longior is sometimes inserted partly into the dorsal 

 fascia of the hand {op. cit. p. 191) ; and Heister (in Haller's Disp. Anat. 

 Select, t. vi. p. 739) describes a Musculus radiceus externus tricomis^ 

 two tendons of which were inserted into the first, and the third into 

 the second metacarpal bone. These may have been instances of the same 

 formation. 



The fully formed muscle and tendon of the accessorius was much 

 more adapted to challenge attention ; but after a careful and prolonged 

 search among the works of the older anatomists (kindly placed within his 

 reach by Professor Sharpey), the author has found that only one incom- 

 plete example has been recorded. The specimen referred to is described 

 by G. Fleischmann (in Abhandl. der physikalisch-medicin. Societat zu 

 Erlangen, 1810, Bd. i. S. 28, with a figure by Loschge, Tafel I. fig. 2). 

 It was an example (found in both arms of a woman) of that variety of the 

 muscle in which the tendon is not inserted at all into the pollex-metacar- 

 pal, but passes bodily into one of the muscular bellies of a double or 

 divided abductor poUicis brevis. Such a specimen was figured by the 

 author in his paper of 1854. The absence of any bony attachment to the 

 pollex-metacarpal seems to have obscured the real nature of the muscle. It 

 was called by Fleischmann " der zweib'duchiger Abzieher des BaumenSy' or 

 *' abductor pollicis biceps.'' It seems to have been the identical specimen 

 obscurely alluded to by Meckel under that name (Muskellehre, S. 517), 

 and mentioned by Cruveilhier under the head of " abductor pollicis brevis " 

 as a double-headed abductor of the thumb. Henle also seems to have fol- 

 lowed this indication of a digastric long abductor of the thumb (Muskellehre, 

 S. 224). 



In 175 subjects in which the author has had this muscle carefully 



