154 THE SENSE OF TOUCH IN ANIMALS 



such as the various forms of Papio, is not noticed, but it militates 

 strongly against the anti-slipping theory of Miss Whipple. 

 Further, the interdigital pads, though prominent, are so soft 

 that a very Httle pressure squeezes them flat, thus ehminating 

 any possible effect the ridges might have in preventing slipping. 

 Cehus fatuellus, Figs. 23, 24, again has on the proximal phalanges 

 of D. 3, 4 of both fore and hind foot a curious bilateral whorl 

 which is too highly developed to be connected with any imagined 

 need for preventing shpping in this surface, largely covered as 

 it is by the adjoining fleshy interdigital pads, but which may 

 well be supposed to be of use in conferring an especial degree 

 of tactile sensibiUty. The short and not very efficient digits 

 of the hand of Macacus cynomologus, Figs. 35, 36, show on the 

 proximal phalanges of D. 2, 3, 4, 5 well-formed eUipses in an 

 unusual position, and under the cover of the interdigital pads, 

 where they would be quite incapable of preventing shpping, but 

 would be useful tactile structures supplementing the three well- 

 developed whorls on the interdigital pads. The hand and foot 

 of Hylohates hainanus, Figs. 41, 42, show an interesting change 

 from most of the Monkeys in the much more longitudinally- 

 placed palmar and plantar ridges, and transverse ridges of the 

 digits, which are more regularly and accurately arranged than 

 is usual in lower forms. These two arrangements are in keeping 

 with the immense use made by Gibbons of the long digits for 

 support and swinging from branch to branch, and of the palm 

 and sole for the grasping of spherical objects, such as fruits. 

 A similar grouping of the ridges is seen in the Orang, but the 

 foot shows more transverse ridges than that of the Gibbon, and 

 the patterns of the digits are still more highly developed. The 

 clumsy shorter hand and foot of the Gorilla, Figs. 45, 46, suggest 

 greater power, but less dehcacy of touch than either the Orang 

 or Gibbon. The Cliimpanzee, Figs. 47, 48, hand and foot agam 

 show much more simphcity of pattern on the digits than the 

 Gibbon, as might be expected from the shorter and less efficient 

 digits of the former, and the difference of their habits. In 

 the case of the human hand and foot it has been pointed out 

 before that the characteristic human arrangements are : first, 



