CHFRCH ON THE MYOLOGY OF THE OEANG UTANG. 85 



thumb independeutly, and are capable of seizing an object in the 

 same way as the Oraugs and Man, i.e. with the fingers on one side 

 and the thumb on the other. 



In the Chimpanzee and the Orang this freedom of motion has 

 been obtained at the expense of the sti'ength of the thumb, in which 

 point they are Tery inferior to Man or the other Quadrumana. 



The hand of the Orang contrasts unfavourably with that of the 

 Chimpanzee, owing to the absence of the Extensor Frioni Internodii 

 Pollicis and the Extensor Froprius Indicls. 



In the rudimental thumb of the Ateles aU. these muscles exist, 

 showing that its development is merely arrested and not suppressed. 



The Muscles of the Posterior Extremity. 



The Iliacus, Fsoas Magnus and Fsoas Parvus presented much the 

 same appearance as in man ; they are flatter, and in accordance with 

 the elongated shape of the pelvis, longer ; beneath these muscles a 

 small one was found, mentioned by Professor Owen,* as present in 

 the Orang, but not in the Chimpanzee, which arose from the ileum 

 in close coiuiection with the Fectus Femoris, passed over and was 

 attached to the capsular ligament of the femur, and was inserted 

 into the trochanter minor. 



The Tensor Vagin<je Femoris was absent ; it is present in the 

 Chimpanzee, small and narrow in the Grorilla (Duvernoy, 1. c. p. 83), 

 and relatively stronger than in man, in the Magot ; it is well deve- 

 loped in the Cehus. 



The insertion of the Sartorius was one inch below the head of the 

 tibia, on its inner surface ; this muscle was well developed. 



The Pectineus in the Chimpanzeef gives off" a slip to the origin of 

 the Sartorius. In the Magot this muscle was very strong, arising 

 from the whole of the anterior edge of the pubes, covering in the 

 origin of the Adductor Brevis, and verging on the Gracilis. 



The Gracilis was proportionately much stronger than in man, and 

 took its origin from a wider space on the pubes. In man its origin 

 covered the space of two inches only, while in the Orang it covered 

 one and a half inches ; it was inserted together with the Semitendino- 

 sus, but below the Sartorius, partly into the tibia and partly into the 

 superficial fascia of the leg ; its insertion extended half way down the 

 tibia, which bone measured six inches, Avhereas in man, where the 

 tibia measured 141 inches, the insertion ot the three muscles, Sarto- 

 rius, Gracilis and Semitendinosus, only extended three and a half inches 

 below the head of the tibia. 



The Semitendinosus was fleshy throughout and, at its lower end, 

 the muscular fibres bifurcated to form two tendons, the superior one 

 being inserted immediately below the upper part of the Gracilis, one 

 and a half inches below the head of the tibia, while the other became 



* Proceedings of the Zoological Society, Vol. i. p. 69, f Ibid. Vol. i. p. 68. 



