ARRANGEMENT OF THE PAPILLARY RIDGES 161 



Lower Animals. 



At the other end of the scale the scanty ridges of a hedgehog's 

 or squirrel's foot would be negligible in preventing slipping, however 

 useful they would be, as I hold, as early organs of touch. Between 

 these extremes the slow loris affords a valuable example to study, 

 with the help of Fig. 61 . The foot, as more concerned with preven- 

 tion of slipping than the hand, is chosen for observation, but with 

 little exception the hand agrees closely with it. On the tips of 



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Fig 61. — Slow loris — right foot. 



four digits, Dl,3,4 and 5, omitting D2 for the moment, the ridges 

 are arranged nearly in a longitudinal direction, and would on that 

 account have little or no effect in preventing slipping of the foot. 

 If this be disputed one can but reply that if the need of preventing 

 slipping in this tiny area were to call forth selective value this is not 

 the arrangement of the ridges that best serves the purpose. It 

 may be remarked here that the pulps of lemurs, the marmoset and 

 squirrel monkey all show this indifferent mode of grouping of ridges. 

 The aborted D2 of the loris, with its hooked nail overhanging the 



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