INTRODUCTION. Vii 



among the quadrupeds, because they can walk on the earth. 

 Some again, who admitted the mammalian nature of the crea- 

 tures, scattered them at intervals through the scale of animated 

 beings, heedless of any distinction excepting the single charac- 

 teristic in which they took their stand, and by which they judged 

 every animal. These are but a few of the diverse opinions which 

 prevailed among the naturalists of former times, among which 

 the most ingeniously quaint is that which places the bat and 

 ostrich in the same order, because the bat has wings and the 

 ostrich has not."^ 



Without reviewing the recorded errors of these observers, we 

 will be content to call the attention of the reader to the following 

 brief account of the structure of flying animals, so that the true 

 position of the bat among them may be definitely fixed. 



There are two distinct types of modification which the verte- 

 brate skeleton has undergone in adapting the animal for flight, 

 both of which depend upon some peculiarity in the structure of 

 the anterior extremities ; and in order to obtain a correct opinion 

 of them we propose to cast a glance at each in turn. 



Plan of bony structure of the wings offying vertebrate animals. 



C I. Wing membrane supported by all 

 fingers — 



Bats (Vespertilio), order of Mam. 

 II. Wing membrane supported by tbe 4tli 



I finger only (which is immensely de- 



veloped), the others remaining free — 

 *- Pterodactyl es, order of Kept. 



a. Bones of carpus separat- 

 ed ; flight maintained by 

 dermal expanse 



r III. Bones of metacarpus 2-3 in number — 

 Bones of carpus united ; Feathers not radiating— 



flight maintained by der- J Livimj birds (Aves)— class. 



mal appendages IV. Bones of metacarpus 4 in number — 



Feathers radiating — 



Archaeopteryx (AvEs) — subclass. 



• Wood, Nat. Hist. I (Mam.), 114. 



