THE FAILURES OF ARBOREAL LIFE 219 



monkeys, for example, that has led to the formation of 

 organs of flight." Certainly there is nothing in the 

 anatomy of Cheiromeles or of Galeopithecus to indicate 

 any inheritance of a power of arboreal leaping. Assuming 

 that the Bats are monophylic and that Cheiromeles might 

 show an evolutionary phase representative of the fore- 

 runners of all the members of the order (an assumption 

 I believe to be by no means justified), one might be 

 inclined to imagine that the specialization of foot-grasping 

 and the consequent adaptation of an inverted position, 

 such as we have noted in Nycticebus, was an early phase 

 of the evolution of true mammalian flight. It is of 

 interest to remark here that more than one existing Lemur 

 shows a definite development of a lateral skin fold such 

 as constitutes, when fully developed, a flying membrane 

 or patagium. Beddard has called attention to such a 

 rudiment in Propithecus, and more recently Anthony 

 and Bortnowsky have described a pleuropatagium in , 

 Microcebus (cheirogaleus) minor under the name of " un 

 appareil aerien de type particulier." 



We will not probe the origin of mammalian flight any 

 further, nor turn aside to inquire if all the flying Mammals 

 grouped as the Cheiroptera, or Bats, have sprung at the 

 same tim^, and in the same manner, from the arboreal 

 mammalian stem ; we will be content to see to what ends 

 this new acquisition led. At first sight, it would seem that 

 the ability to fly would be an enormous asset to a Mammal 

 already passed through the apprenticeship of arboreal 

 life. A flying animal knows no limits of habitat or 

 environment; geographical barriers, which limit the 

 activity and spread of the stock from which it sprang, 

 offer no unsurmountable boundaries to its enterprises. 

 Indeed, the geographical distribution of the Cheiroptera 

 demonstrates the reality 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 



