CHAPTER I 



INTRODUCTION 



EFINITION of a Bird. Strange as it may seem, the old proverb that 

 "A bird is known by its feathers," finds such exemplification in the 

 science of to-day that it has actually become the scientific definition 

 of the Class. It was formerly supposed that birds possessed a 

 number of peculiar features, but, says Mr. Ridgway, "the most recent investiga- 

 tions of comparative anatomists have gradually eliminated the supposed exclu- 

 sive characters of birds, as a class of the Animal Kingdom, until only the single 

 one mentioned above, the possession of feathers, remains." As Dr. Stejneger 

 very aptly expresses it, " No bird is without feathers, and no animal is invested 

 with feathers except the bird." 



From the fact that in most systematic arrangements of the Animal Kingdom 

 the Class embracing the birds is usually made to precede the mammals, it might 

 be supposed that the birds were more or less closely related to them. As a matter 

 of fact this is not so, for, according to Beddard, beyond the circumstance of 

 " warmbloodedness and resemblance of some of the more simple forms of feathers 

 to hairs, there is nothing to be said in behalf of a kinship between birds and mam- 

 mals." In some ways birds are undoubtedly the highest of the vertebrate 

 animals. Their body temperature, higher than that of any other animals, is 

 one index of their intense activity; their skeleton is perhaps more modified from 

 the general type than that of mammals, their "arrangements for locomotion, 

 breathing, and nutrition are certainly not less perfect," and it is, in fact, "only 

 when we emphasize the development of the nervous system and the closeness of 

 connection between mother and offspring, that the mammals are seen to have a 

 right to their preeminence over birds." 



It has long been settled with definiteness that the Class of birds is very closely 

 allied to the Class of reptiles ; for even at the present time, that is among living 

 birds and reptiles, there are numerous structural points in common. It is, of 

 course, perfectly easy to distinguish between a bird and a reptile as each exists 

 at present, the most obvious difference being the warm blood and outer covering 

 of feathers in the bird, and the cold blood and usually scaly covering among 

 reptiles. On account of unfortunate breaks or gaps in the paleontological record, 

 we are, with the exception of the evidence afforded by Archaeopteryx, in ignorance 

 of the precise steps in the transition from one Class to the other, and may always 

 remain so, but as was long ago pointed out by Huxley, Cope, Marsh, and others, 

 it is probably in the group of extinct dinosaurs that we must look for evidences of 



