CHAPTEE I 



INTRODUCTION 



Definition. "A Bird is a feathered biped/' This popular 

 saying undoubtedly furnishes a definition in the world of 

 to-day, since no other existing creature has a clothing of feathers, 

 and even the word " biped " is thus superfluous. 



The above should, however, be somewhat expanded, in order 

 to shew in greater detail the differences between Birds and other 

 Vertebrata. Care must nevertheless be taken to avoid the fault 

 common to many modern definitions, of giving an abstract 

 of the main characteristics of the object, rather than a clear 

 guide to distinction. 



Dr. Gadow l defines Birds as " oviparous, warm-blooded, amniotic 

 Vertebrates, which have their anterior extremities transformed 

 into wings. Metacarpus and fingers carrying feathers or quills. 

 With an intertarsal joint. Not more than four toes, of which 

 the first is the hallux." 



Much of this the beginner might well postpone, his attention 

 being solely drawn to the external characters ; though of course 

 those that are internal are by no means to be subsequently 

 neglected. Indeed no satisfactory progress can be made in the 

 serious study of Ornithology, or the Science of Birds, without a 

 competent knowledge of their Anatomy and Development ; while, 

 though at present comparatively few fossil remains of Birds have 

 been found, some of them are of the highest importance, and there 

 is every probability of future discoveries throwing much light not 

 only on the mutual relationships of Birds among themselves, but 

 also on their connexion with the Reptilia. Birds are, in fact, only 

 extremely modified Eeptiles, the two Classes forming the Saur- 

 opsida of Huxley, one of his three primary divisions of Vertebrata. 



1 P.Z.S. 1892, p. 236. 

 VOL. IX | B 



