224 BARON NOPCSA ON THE [Feb. 19, 



adapt fore and hind limbs and tail to the suppoi't of the patagium, 

 whereas in a generalised feathered animal only the feather- 

 supporting elements need become affected by violent specialisation. 

 The development of the posterior limb in such an animal is but 

 little, if at all, affected by the development of flight (foot in Eagle, 

 Parrot, Woodpecker, Nightingale, Goose, Stork, Ostrich, &c.). 



As to flight itself we have to distinguish, as pai'tially already 

 pointed out by Dollo, three distinct stages of evolution : first 

 parachute or passive flight, then flight by flapping the wings or 

 flight hy force, and lastly soai-ing ov flight by skill. 



As Langley and Lucas pointed out in their highly interesting 

 papers, the soaring birds lack carrying power (in accordance with 

 which fact the crista sterni is often comparatively feebly 

 developed), while flight by flapping of the wings, as shown by 

 the generally soaring Eagle when carrying prey, enables the 

 animal to support a good deal of w^eight. 



That soaring birds show a shai-ply pointed wing, while birds 

 that fly mainly by flapping display a wing with a more or less 

 rounded outline, is well known. 



After these preliminary, but I think essential, observations, 

 I shall now point out some characters of Pterosavirs, flying 

 Mammals, Dinosaurs, and Birds that have not yet been brought 

 together. 



Pterosaurs. 



The Dimor])hodon, till now the -earliest-described long-tailed 



Text-fig. 74. 



Hind limb of Dimorphodon 



Pterosaur, shows 'in its hind limb no sign whatever of cursorial 

 locomotion (text-fig. 74). The metatarsals 14 are equally developed, 



