No. 448.] 



CLASSIFICATION OF BIRDS. 



It may naturally be asked, what are some of the chief reasons 

 why the classifiers of this group of vertebrates do not exhibit a 

 greater unanimity — a fact more remarkable when we come to 

 consider that a dozen or more of those classifications coming from 

 the pens of competent ornithologists appeared all within a very 

 few years of each other. It is certainly not due to the fact that 

 it has been demonstrated that birds have arisen from a prehistoric 

 and extremely ancient stock of animals in common with the Rej)- 

 tilia, for knowledge of this character ought to have the tendenc} 

 to harmonize views and opinions rather than to intnKhuc the 

 element of disagreement among them. We may eliiiiiti:itc i<i<». 

 I think, any difficulty that has arisen from the discovery of the 

 few fossil forms of birds we have come in possession of, for nian\ 

 of these belong to the minor groups of existing birds, while others 

 are not calculated to disturb a natural classification. Indeetl, in 

 some instances, they shed light on the subject. Again, in that 

 existing birds are so completely differentiated from all other 

 classes of animals now living upon the surface of the earth, ought 

 to make them the easier to classify. They alone possess feathers 

 and this establishes a line of demarcation for them, standing 

 between the group and the nearest mammals or reptiles, quite as 

 clearly defined as the possession of a mainspring separates all 

 modern watches from an hourglass. The problem then presents 



itself in this wise, to ascertain the true relationships both near 



and remote existing among all living birds, and then prepare as 

 simple a scheme as possible expressing these relationshii)s \w 

 terms that shall be in harmony with the classification schcn)cs 

 adopted in the cases of other classes of animals. In doin- this, 

 one of the first diflftculties to arise is the marked homogeneity ot 

 the group. It is like classifying so many thousands ot black, 

 leather-covered hand cameras ; they all look a good deal alike on 

 their outsides, and the task would be equally difficult were ue 

 not permitted to examine into their interiors and ascertain the 

 differences in their other parts, as the different kinds of lenses, 

 finders, shutters, and other contrivances. Exactly the same 

 thing obtains with birds. The great variance of opinions in the 

 premises at the outstart is due to the difference in the amount 

 of knowledge possessed by the different classifiers, especially as 



