532 Mr. J. Wood on Variations in Human Mijology. [May 23, 



the posterior carpal ligament, to the ulnar side of the middle and ring- 

 Jingers, joming the extensor aponeurosis by separate, slender, flat tendons. 



20. Extensor minimi digiti. — In nearly half the number of subjects 

 was the tendon of this muscle doubled (fig. 5, c). In one (No. 3) 

 there were, further, two distinct muscular bellies. In two subjects 

 (JN'os. 29 & 34) the additional tendon was inserted with the common 

 extensor tendon into the ring-finger, as in the Orang, Apes, Monkeys, 

 Eabbit, Hedgehog, &c. In the Cat and Dog the third and second digits 

 also are supplied by it. 



21. Extensor indicis and Extensor medii digiti. — In two subjects 

 (Nos. 8 & 27) the indicator was provided with a double tendon, showing 

 the first tendency to the formation of a special extensor of the middle 

 finger, such as that found as a distinct muscle in the remarkable ar- 

 rangement seen in fig. 5 (a). Both these are constant muscles in the 

 Apes and Monkeys. 



22. Extensor ossis metacarpi pollicis. — An increase in the number of 

 tendons of this muscle was seen in 16 subjects out of 36, i. e., nearly half. 

 In four the tendon was simply doubled, both being inserted into the 

 base of the first metacarpalbone. In four others one of the two tendons 

 was inserted into the trapezium. In one (No, 25) the tendon was triple, 

 two being inserted into the metacarpal, and one into the trapezium. 

 In seven instances the tendon sent off a slip which gave part origin to 

 the fibres of the alductor pollicis hrevis. These sometimes formed a 

 separate muscle. In four of these there were two tendons only, one 

 inserted into the base of the metacarpal bone, and the other going to the 

 abductor. In two (Nos. 20 & 31) there were three tendons, one to 

 tbe metacarpal bone, another to the trapezium, and the third to the 

 abductor pollicis. Such an arrangement has been recorded by Maca- 

 lister {op. cit. p. 13). In one (No. 11) there were no less than four 

 tendons, three of which were inserted into the middle of the shaft and 

 base of the metacarpal bone, and one went to the abductor. In the 

 last subject the extensor primi internodii pollicis was entirely absent, 

 increasing the similarity in the arrangement of these muscles to that 

 found in the Chimpanzee and Orang. In two other subjects (Nos. 6 & 

 21) the muscular part of the extensor primiwas entirely blended with 

 that of the extensor ossis metacarpi, though the tendon was separate 

 and its insertion distinct, into the base of the first phalanx of the 

 thumb. 



23. Interossei manus. — Three specimens of the " Palmar interosseus of 

 the thumb " of Henle were found. In two subjects (Nos. 4 & 20) the 

 first interosseous space was occupied by two muscles, one, the "Abductor 

 indicis " of Albinus and the older anatomists, and the other the " In- 

 terosseus prior indicis" of that author (the "Extensor tertii internodii 

 indicis" of Douglas (Myograph. Comp. p. 181). 



24. Among the miscellaneous specimens in the upper extremity were 



