PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
55 
climbing. If it did so it would necessarily throw the leg and foot out- 
wards at the same time, in consequence of the fact that the knee is 
flexed and never straight in the Orang ; as a matter of fact, in climbing 
upwards the ape applies the sole of the foot to the tree, whilst the thigh 
is abducted and rotated out. The ape thus climbs in a different fashion 
from that in which a boy would climb a pole, with thighs adducted and 
rotated in and with the knees hard pressed inwards. Pick states, 
however, that man in climbing with naked feet, as for example, the child 
of a Malay negro, will climb as the ape does, with the soles of the feet 
applied to the trunk of the tree and with thighs rotated out. This action 
of flexion of the femur with rotation outwards is not the function of the 
scansorius but of the ilio-psoas. In this sense, therefore, the name 
scansorius is inapplicable. Pick admits that the scansorius may be 
brought into action when the ape is climbing from one branch to 
another, when, he observes, the animal very frequently performs this 
movement with flexed thigh rotated inwards. 
The scansorius muscle was first described and named by Traill 
(quoted by Bischoff, from Memoirs of the Wernerian Nat His. Soc., Vol. 
III., p. 29, 1821) in the Chimpanzee. According to TestuP there is fre- 
quently found in man a small fasciculus more or less differentiated from 
the gluteus minimus anteriorly, which passes to be inserted into the 
great trochanter ; this Testut considers the representative of the scan- 
sorius in man. This fasciculus, he adds, exists normally in a large 
number of mammals. 
The weak development of the glutei muscles in general in man is 
to be ascribed to the erect attitude, whilst again the comparatively 
strong development of that part of the gluteus maximus in the ape which 
proceeds down the thigh — in my Orang as far as the external condyle — 
is associated with climbing, the thigh being carried back with consider- 
able force by that part of the muscle. 
*The Tensor fascice femoris was entirely absent in my Orang. Bischoff 
states regarding it that the fascia lata is more weakly developed than 
in man, and the muscle is scarcely present as an independent muscle in 
any instance, but may be represented by a few fibres derived from the 
anterior part of the gluteus maximus. This agrees with the freer and 
more isolated action of the thigh muscles in apes, as is necessary in 
climbing, whilst in man these muscles are required to be more firmly 
bound together in the erect position and in walking. 
Loc. cit., Vol. I, pt. 2, p. 837. 
