Vice-President's Address, 9 



there was a closer approximation to the proportions of the 

 anthropoid foot than is found among modern feet. 



The muscular arrangements in the anthropoid foot very 

 closely resemble those of the hand, in which the disposition 

 of the abductor or dorsal interosseous stratum of muscles 

 enables us to fix the third digit as the middle line of both 

 hand and foot. In the foot of man, the second toe now 

 provides the plane of the middle line, and in the foot of the 

 gorilla the transition stage may be seen. 



Again, the act of walking erect has necessitated a control 

 of the movements of the foot, of a kind quite different from 

 that required by the shuffling gait of the ape, and the outer 

 border of the foot is supported by a muscular arrangement 

 which is peculiar to man's foot. This is i\iQ peroneus tertius 

 muscle, which, from its nerve-supply, is regarded as a special 

 development of the long extensor muscle of the toes. On 

 the dorsum of the foot there is another muscle of much 

 evolutionary importance, viz., the extensor hrevis digitorum. 

 In man, this muscle has entirely lost all association with the 

 extensor aspect of the fibula, but in some departments of the 

 animal kingdom its entire origin is situated upon the fibula. 

 The transition stages between these two extreme conditions 

 have been fully observed, and we may, therefore, regard the 

 human position of this muscle as an adaptation to the 

 requirements of the erect attitude. 



Another direct evolution of the erect attitude is to be 

 found in the massive character of the gastrocnemius and 

 soleus muscles of the calf of the leg. Among the lower 

 human races and apes these muscles are not prominent, 

 partly because of their walking gait, and partly because 

 of the greater backward projection of the heel-bone (os 

 calcis). 



The muscles of the thigh and buttocks present several 

 interesting evolutions. The Hamstring or Flexor group is 

 well developed, but it has been reduced in number through 

 the inclusion of an important member with the adductor 

 magnus, in which it is described as the ischial head. The 

 lower end of this muscle (ischial head of adductor magnus) 

 has, moreover, lost its tibial attachment, and become associated 



