THE FAILURES OF ARBOREAL LIl'i: l>1!. 



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

 organs of flight." Certainly there is nothing in tho 

 anatomy of Cheiromeles or of Galeointhecns \^^ 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 tlu* fore- 

 runners of all the members of the order (an assumption 

 T believe to be by no means justified), one miglit be 

 inclined to imagine that the specialization of foot -grasping 

 and the consequent adaptation of an inverted ])osition, 

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

 of the evolution of true mammalian fliglit. it is of 

 interest to remark here that more than one existing Lennir 

 show^s a definite development of a lateral skin fokl sueh 

 as constitutes, when fully developed, a flying mem))rane 

 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 fliglit 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 t hat 

 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 hal)itat or 

 environment; geographical barriers, whieii limit tho 

 activity and spread of the stock from whieh il sprang, 

 offer no unsurmountable boundaries to its enterjirisej?. 

 Indeed, the geographical distribution of the Cheiroptera 

 demonstrates the reality of this advantage. 



The power of flight, whilst offering an abundant ehange 

 of habitat, affords also an almost unlimited range of 

 dietary; it facilitates escape from enemies, and provides 



