1907.] 



ORIGIX OP FLIGHT. 



227 



to be met with among Bats, whose crawling locomotion is familiar 

 to every student. 



The elongation and attenuation of the hind feet in Nyctodactylus 

 (text-fig. 77) are also characters that demand mention, and a 

 similar elongation is again to be met with in the tailless Vampires. 



An interesting featvire is the co-ossification of numerous dorsals 

 in Nyctodactyhis and the nearly allied European genus Orniiho- 

 cheirus. 



Text-fio-. 77. 



Hind limb of Xi/ctodacti/Tus. 

 (Photograph of specimen in the British Museum.) 



A Triassic long-tailed Pterosaurian, Trihelesodon (the detailed 

 description of which I intend publishing on some other occasion), 

 .shows much the same propoi-tion between total length of hind 

 and fore limbs as does Galeojnthecus ; and, although Galeopiihecus 

 proves to be in no way related to Chiroptei-a, still we must suppose 

 that the whole oi'der Chiroptera, considering the patagium, passed 

 through a Pteromys- and a Gcdeopithecus-like stage in the course of 

 its evolution. 



Since, as already pointed out, a patagium requires many spear- 

 like supports, and since in arboreal animals fore and hind lirabs 

 are to the same extent used for running and leaping, it is evident 

 that primarily fore and hind limbs must have become to the same 

 extent used for the suppoi't of the patagium, which necessarily had 

 to take origin at the centre of gravity between humerus and femur. 



As soon as such a potentially flying animal became actively 



