the Chimpanzee and others of the Primates. 347 



pied the lower third of tlie radius, and was exceedingly weak. 

 The radial extensors of the carpus were separate and nearly 

 equal ; and the short supinator was very large, equal to the 

 combined round and square pronators in weight ; the posterior 

 interosseous nerve pierced it as usual. Neither the tensor 

 ligamenti annularis anterior nor posterior (Gruber and Cru- 

 veilhier) was present. 



The extensor digitorum longus sent single tendons to the 

 second, third, fourth, and fifth fingers, and was not divisible 

 i^adily, as was the case in Wilder's animal. This author, 

 Vrolik, and Moore describe the absence of the little-finger 

 tendon of this muscle. 



The extensor minimi digiti went to the fifth finger alone, 

 by a single tendon. The extensor carpi ulnaris was only half 

 the size of either of the radial extensors, and had a distinct 

 ulnaris-quinti tendon prolonged onwards to the first phalanx 

 of the little finger. The indicator sent a tendon to the middle 

 finger, and arose as usual ; in Wilder's specimen it only sup- 

 plied the index, and arose a little lower than usual. Prof. 

 Humphry found the middle-finger slip in his animal {Joe. cit. 

 p. 267). 



The extensors of the thumb agreed exactly with those de- 

 scribed by Prof. Humphry, except that the first of his muscles 

 went to the scaphoid and metacarpal bones, whereas in ours it 

 ended in the trapezium ; the second was, as he describes, 

 attached to the metacarpal bone, and the third to the last pha- 

 lanx of the thumb ; the second of these was in size equal to 

 the sum of the other two. Vrolik, Wilder, and Wyman have 

 found the same arrangement.- 



The lumbricales were like those of man ; and the fourth 

 arose from its proper tendon, not as in Wilder's specimen. 

 All the thumb-muscles were as in man. The abductor was 

 not split into Sommerring's slips ; and the flexor brevis did 

 not extend beyond the first phalanx, as Humphry found in 

 his specimen. The interossei were also arranged on the 

 human type ; these muscles, though usually regular, are not 

 always absolutely constant in this mode of arrangement in 

 Quadrumana. Thus the disposition in Ateles fidiginosus (in 

 which the thumb is only represented by a rudimentary meta- 

 carpal bone little more than half the length of the second 

 metacarpal) is as follows : — Of palmar interossei there are, 

 1st, a normal first palmar, from the second metacarpal to the 

 index finger; 2ndly, a thin sujjerficial palmar interosseus 

 arising from the front of the third and fourth metacarpal bones, 

 and inserted into the ulnar side of the first phalanx of the 

 index finger ; this muscle looks like an adductor pollicis with 



