366 Contributions to the 



which is inserted into the base of the second phalanx of 

 the thumb. The thumb has thus become merely an aid in 

 the grasping of the fingers, with little or no independent 

 action. A like arrangement existed in Duvernoy's Go- 

 rilla, but in Prof. Wyman's Gorilla, and in his and Traill's 

 Chimpanzees, this muscle did not exist separate from the 

 rest. Tyson says that the muscles of the thumb differed 

 not from the human, but there was no tendon to the 

 Thumb in Vrolik's specimen. In the lower Quadrumana, 

 when there is any tendon for the thumb it generally comes 

 from the common flexor ; there was none in Ateles Panis- 

 cus, whose thumb is rudimentary ; in the Howling jNIon- 

 key there were four tendons, — one to the thumb, but 

 none to the little finger. 



The short muscles of the thumb were all present, but* 

 thinner and less distinct than in man ; they exist in the 

 Gorilla and Howling-Monkey, but not in Ateles Paniscus, 

 except perhaps a very little rudiment. The Extensor lon- 

 gus poinds [secnndi internodii) is present generally in the 

 Quadrumana. The Extensor brevis pollicis [prinii inter- 

 nodii) was quite as large as the preceding, not smaller as 

 in man, and was inserted into the radial side of the base of 

 the metacarpal of the thumb, as in the specimens of Wyman 

 and Yrolik ; Tyson says the insertion was as in man. In 

 the Gorilla, Prof. Wyman does not mention any peculiarity; 

 and Duvernoy says it is as in man, but that it is want- 

 ing in the Chimpanzee, the Abductor long-its taking its 

 place; in this Chimpanzee it was confounded with the 

 latter only above. It was wanting in the Howling-Mon- 

 key, and ill Prof. Wyman's Cynocephalus was joined to 

 the Abductor, which goes to the trapeziiuii. The Abductor 

 longus pollicis {Extensor ossis metacarpi) was inserted into 

 the trapezium, as in the specimens of Prof. Wyman and 

 Vrolik, and in Prof. W.'s Cynocephalus, but in the Howl- 

 ing-Monkey it is as in man. In the left arm of Ateles 

 Paniscus Mr. Folsom says it was present, but Mr. Moore 



