VI. 



The Significance of the Bird's Foot. 



To say that birds have been evolved from reptiles is to utter one of 

 the tritest of zoological commonplaces ; but as to the nature of 

 the particular reptilian stock which blossomed out into birds, there 

 is by no means a complete accord among zoologists. Some have 

 suggested a connection between the birds and the pterodactyles : a 

 connection which, if it ever existed, must have done so before either 

 class obtained the power of flight. For it is hardly possible that 

 animals which had developed the pterodactyl form of flying organs 

 would then proceed to change them into feathered wings. Others, 

 led away by the resemblances between the RatitcB and the ornitho- 

 podous Dinosaurs, have traced the pedigree of flying fowl from the 

 latter through the former. But the striking resemblances between 

 the feet of these groups may, in all probability, be set down as 

 produced by similar needs and conditions, especially since both have 

 the same reptilian origin. For even in mammals we find a very bird- 

 like hind-limb, with coalesced metatarsals, in the Jerboa, which walks 

 in the same manner as a bird when not performing its prodigious 

 leaps. Conversely, there is a strong superficial resemblance between 

 the hind-limbs of an ostrich and a horse. 



Even Professor Fuerbringer, however, thinks that the first birds 

 were probably terrestrial, afterwards diverging into climbers on rocks 

 and trees, and inhabitants of swampy regions, the latter stock giving 

 rise to waterfowl. 



It is not without considerable diffidence that I venture to propose 

 a different theory, namely, that birds originated from an arboreal reptile, 

 which had acquired tree-haunting habits before it began to develop 

 wings, and that all terrestrial and aquatic forms of bird-life can be 

 derived from arboreal ancestors. 



If we survey the various divisions of the vertebrates, we shall 

 find, almost invariably, that the first steps towards flight are taken by 

 already arboreal forms. Such forms, taking short flights by means of 

 a skinny parachute, are found among reptiles, in the " flying " geckos 

 (Ptychozoon), and the " flying " dragons {Draco). Among mammals, we 

 may cite the "flying" Sciuridas, the Anomalures, and especially 

 Galeopitheciis, which, with its interfemoral membrane and long webbed 

 fingers, plainly indicates the way in which the bats probably 



