382 Zoological Society : — 



the length of the femur), adds to the appearance of its superior rela- 

 tive thickness. Absolutely the thigh is not of greater circumference 

 at its middle than is the same part in man. 



The chief difference in the leg, after its relative shortness, is the 

 absence of a " calf," due to the non-existence of the partial accumu- 

 lation of carneous fibres in the upper half of the gastrocnemii muscles, 

 causing that prominence in the type-races of mankind. In the Go- 

 rilla the tendo-achillis not only continues to receive the "penni- 

 form" fibres to the heel, but the fleshy parts of the muscles of the 

 foot receive accessions of fibres at the lower third of the leg, to which 

 the greater thickness of that part is due, the proportions in this 

 respect being the reverse of those in man. The leg expands at once 

 into the foot, which has a peculiar and characteristic form, owing to 

 the modifications favouring bipedal motion being superinduced upon 

 an essentially prehensile quadrumanous type. The heel makes a 

 more decided backward projection than in the Chimpanzee ; the heel- 

 bone is relatively thicker, deeper, more expanded vertically at its 

 hind end, besides being fully as long as in the Chimpanzee. This 

 bone, so characteristic of anthropoid affinities, is shaped and propor- 

 tioned more like the human calcaneum than in any other ape. The 

 malleoli do not make such well-marked projections as in man ; they 

 are marked more by the thickness of the fleshy and tendinous parts 

 of the muscles that pass near them, on their way to be inserted into 

 parts of the foot. Although the foot be articulated to the leg with 

 a slight inversion of the sole, it is more nearly plantigrade than in 

 the Chimpanzee or any other ape. The hairy integument is con- 

 tinued along the dorsum of the foot to the clefts of the toes, and 

 upon the first phalanx of the hallux : the whole sole is bare. 



The hallux (great toe, thumb of the foot), though not relatively 

 longer than in the Chimpanzee, is stronger ; the bones are thicker in 

 proportion to their length, especially the last phalanx, which in 

 shape and breadth much resembles that in the human foot. The 

 hallux in its natural position diverges from the other toes at an 

 angle of 60 deg. from the axis of the foot ; its base is large, swelling 

 into a kind of ball below, upon which the thick callous epiderm of 

 the sole is continued. The transverse indents and wrinkles show the 

 frequency and freedom of the flexile movements of the two joints of 

 the hallux : the nail is small, flat, and short. The sole of the foot 

 gradually expands from the heel forward to the divergence of the 

 hallux, and seems to be here cleft, and almost equally, between the 

 oase of the hallux and the common base of the other four digits. 

 These are small and slender in proportion, and their bases are en- 

 veloped in a common tegumentary sheath as far as the base of the 

 second phalanx. A longitudinal indent at the middle of the sole, 

 bifurcating — one channel defining the ball of the hallux, the other 

 running towards the interspace between the second and third digit — 

 indicates the action of opposing the whole thumb (which seems rather 

 like an inner lobe or division of the sole), to the outer division ter- 

 minated by the four short toes. What is termed the "instep" in 

 man is very high in the Gorilla, owing to the thickness of the carneo- 



