" ARBOREAL MAN " 233 



of this advantage. The power of flight, whilst offering an abundant change 

 of habitat, affords also an almost unlimited range of dietary ; it facilitates 

 escape from enemies, and provides a ready means of avoiding local over- 

 crowding, 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 

 world-wide distribution of the Bats, are evidence of this. 

 Yet, when all this is said, there is a great " 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 which 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 

 specialised as " wings ; " they are no longer useful for grasping, for touch, 

 for examination and for all the other functions which we have seen so 

 essential in the final education of the neopallium which makes for real 

 evolutionary progress. No matter from what 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 very factor which enabled 

 them to take their momentous step had been altogether absorbed in taking 

 the step. 



Even the vastest possibilities of omnivorism, therefore, are 

 not enough to open a path of progress. On the contrary, the 

 more assured the omnivorism, the more certain is the loss of a 

 " vital evolutionary asset." It is possible, of course, that the 

 flying mammals were driven by some adversity to an aerial 

 habitat ; but it is far more likely that their failure arose through 

 faulty food-adaptation of some sort, be it only through unsymbiotic 

 use of plant products. And I would lay it down that wherever 

 in evolution we meet with a failure of retinens vestigia jama, we 

 may conclude that the ancestors of the order have either failed 

 in symbiotic behaviour towards the plant, or, worse still) have 

 sold their birthright for a potage an gras. 



We have no reason for thinking that feeding upon slugs, worms, 

 larvae, insects, etc., calls for any great aesthetically or educa- 

 tionally valuable exercises on the part of the limbs. Nor are such 

 habits conducive to a high mutual specialisation of the limbs ; 

 nor to a recession of the snout region. On the contrary, inasmuch 

 as they are in opposition to the law of concord in Nature, they 



