220 ARBOREAL MAN 



a ready means of avoiding local overcrowding, rivalry, 

 or temporary local adversity. All these things are assets 

 — enormous assets — in the preservation and multiplication 

 of the type; and the specific richness, the enormous 

 numbers of individuals, and wide- world distribution of 

 the Bats, are evidence of this. But it must be remembered 

 that, despite the undoubted successes of the flying 

 Mammals in these limited directions, there has been an 

 evolutionary stasis in the group extending over a very 

 long geological period. They have obviously gained 

 their freedom, and their specific plasticity at the expense 

 of some very vital evolutionary asset. The thing which 

 they have lost in taking to an aerial life is the very thing 

 w^hich they won in their arboreal life, the factor which 

 made their aerial enterprises possible — the emancipation 

 of the fore-limb. Their fore-limbs have become purely 

 specialized as " wings " ; they are no longer useful for 

 grasping, for touch, for examination and for all the other 

 functions Avhich we have seen are so essential in the final 

 education of the neopallium \\hich makes for real evolu- 

 tionary progress. No matter from \\ liat sources, and by 

 what routes, the whole of the flying Mammals comprised 

 within the limits of the order Cheiroptera were derived, 

 we may regard them all as animals which, having sacrificed 

 the very valuable freedom of the fore-limb to the powers 

 of flight, had flourished exceedingly as a consequence of 

 their enterprise, but had progressed but little in real 

 evolution, since the ver}- factor which enabled them to 

 take their momentous step had been altogether absorbed 

 in taking the step. 



