272 PROFESSOR OWEN ON THE EXTERNAL CHARACTERS 



soon surpass those of the kinds of Gyrencephala, Lissencephala, and Lyencephala now 

 living upon the earth. 



Agreeably, therefore, with the above estimate of the value of cerebral characters, the 

 Troglodytes Gorilla, like the T. niger and the Pithecus Satyrus, remains with the Gibbons 

 and lower Quadrumana, and stands apart in a distinct subclass from the genus Homo. 



I next proceed to consider the value and application of the characters afforded by the 

 limbs of the Gorilla. 



In the terminal segment of the fore limb the pollex is stunted ' ; the other digits, 

 lengthened and strengthened, with their proximal and especially their middle phalanges 

 expanded for the support of the broad callosities on which the beast walks : the length 

 of these digits enables them also to bend upon the palm and grasp or cling to a bough, 

 and the hand is thus adapted for movement in trees, as well as for the quadrupedal 

 progression on the ground : but, in the same degree, it is deprived of the faculty of 

 delicate digital prehension or " manipulation." The hand of the Gorilla offers a slight 

 advance upon the type of that in the Chimpanzee or Orang by its greater relative 

 breadth : the entire fore or upper limb is also rather shorter in proportion to 

 the body. Compared with the modifications of that limb in Man and the resultant 

 powers of the member, the fore limb of Quadrumana appears to me to be inferior to that 

 in Bimana in a greater degree than it is superior to the fore limb in the Squirrel or any 

 pentadactyle Unguiculate ; the difference between the Gorilla and Man in this particular 

 I regard therefore as one of ordinal value. In the lower or hind limb the difference 

 between the Gorilla and Man is still more manifest and important in its consequences. 

 The deficiency of length in proportion to the trunk is greater than the excess of length 

 of the upper limbs. The foot is made a true hand, or grasping organ, by the opposition 

 of a thumb to the other digits, as well as by the length and flexibility of the toes^ 

 Accordingly the innermost digit presents as well-marked modifications to act the part 

 of a ' thumb ' as affect it in Man in order to act the part of a ' great toe ': in both cases 

 the whole tarsus has been subject to coordinate modifications''. The other four digits 

 in the Gorilla present a greater excess of length compared with Man than in the upper 

 limb ; they are also more approximated to each other, and are bound together in a 

 common ligamentary sheath to nearer their extremities than in Man, and are collectively 



Chimpanzee, affirms : — " Le cerveau est absolument de la meme forme et de la meme proportion, et il ne pense 

 pas : y a-t-il une preuve plus evidente que la raatiere seule, quoique parfaitement organisee, ne pent produire ni 

 la pensee ni la parole qui en est la signe, a moius qu'elle ne soit anim^e par un principe superieur?" (Hist. Nat. 

 xiv. p. 61.) 



' In the Gorilla the length of the entire pollex only equals that of the metacarpal of the middle finger, and is 

 rather more than three-eighths the length of that finger : in Man the pollex equals the metacarpal and nearly 

 the whole of the first phalanx of the middle finger, and is almost two-thirds the entire length of that finger, 

 including the metacarpals in both cases. (Memoir, No. VII., Trans. Zool. Soc. vol. iv. p. 11. pi. 10.) 



' Memoir, No. VII., pi. 11. fig. 2. • lb. figs. 1 & 2. 



