THE FOOT IN THE ANTHEOPOMORPHA. 481 



tlie same in tlie Orang ; in the Chimpanzee it is as twenty- 

 four to ten ; and, in the Gorilla, about the same (twenty- 

 three to ten in the specimen measured). 



The hallux has not more than one-fourth of the length 

 of the foot in the Orang; in the Gorilla less than five- 

 twelfths ; in the Chimpanzee and in Hylobates a little more. 



In the second digit of the pes of the Orang and the 

 Chimpanzee, the phalanges, taken together, are longer than 

 the metatarsal hone of the digit ; in the Gorilla, they are 

 about equal in length to the metatarsal. The calcaneal 

 process is longest, strongest, and broadest in the Gorilla. 

 In the astragalus the articular surface for the tibia is 

 broadest in the Gorilla ; but, in this Ape, as in the others, it 

 is inclined a little inwards when the foot is in its natural 

 position; and the surface for the external malleolus is 

 oblique, and looks upwards as well as outwards. 



It is a mistake, however, to suppose that the disposition 

 of these surfaces has anything to do with the more or less 

 marked tendency of the plantar surface to turn inwards, 

 and of the outer edge of the pes to be directed downwards, 

 which is observable in all the Anthropomorpha. This 

 tendency is the result of the free articulation between the 

 scaphoid and the cuboid, on the one hand, and the as- 

 tragalus and the calcaneum on the other ; the consequence 

 of which is that the distal portion of the pes, with the fii'st- 

 mentioned bone, being pulled by the tibialis anticus, easily 

 rotates round its own axis, upon the surface presented by 

 the astragalus and calcaneum. This ready inversion of the 

 sole must as miich facilitate climbing, as it must interfere 

 with the steadiness of the foot in walkinsr. 



The distal surface of the entocuneiform is much inclined 

 inwards in all the Anthropomorpha, and is convex from side 

 to side, or subcylindrical. The metatarsal bone of the 

 hallux presents a con-esponding articular concavity to this 

 surface, and has a great range of motion in adduction and 

 abduction. The inward inclination of the articular facet 

 of the entocuneiform, and its consequent separation from 

 the facet upon the mesocuneiform for the second digit, is 



2 I 



