490 PROCEEDINGS OF THE ACADEMY OF [1898. 



case of many of them their general anatomy has been investigated, 

 and their biology as a whole given weight. My views upon the 

 classification and systematic position of some of these families or 

 species now in my mind, have been briefly abstracted and published, 

 either in The Ibis of the British Ornithologists' Union, or in the 

 Proceedings of the Zoological Society of London. Others there are 

 that have not been so noticed. 



Prior to passing to the aforesaid subject-matter in chief how- 

 ever, it may be as well first to pay some attention to the morpholog- 

 ical characters of birds with special reference to their use in determin- 

 ing a scheme for the natural classification of the Class. By the 

 natural classification of Aves is meant an orderly arrangement of 

 existing birds into major and minor subdivisions according to their 

 true affinities as they actually obtain in nature. That a real relation- 

 ship exists among certain and various tribes of birds, since the time 

 they have, through their evolution, become differentiated from their 

 remote reptilian stock, is a fact that it is feared those who attempt 

 their taxonomy do not always keep impressed with sufficient 

 strength upon their minds. Consequently we often hear of this 

 classifier's arrangement, and that classifier's arrangement or scheme, 

 just as though no real affinities existed, whereas it is the duty of 

 each and every one attempting a taxonomic scheme to discover pre- 

 cisely how the avian tree has thrown out its branches and its twigs, 

 and, if possible, determine the points from where they sprung. 

 Equally useless is it to attempt a classification of birds by selecting 

 for the purpose the ornis of any particular area of the earth's sur- 

 face. Those that enter upon the task by applying to taxonomic 

 ornithology the birds occurring within arbitrary political boundaries 

 as mapped out by man will fail utterly, and such a piecemeal, pro- 

 visional classification will, with the greatest certainty, be broken up 

 the moment the first far-seeing taxonomer tests it with the morpho- 

 logical facts gathered from the entire class, both existing and ex- 

 tinct, as far as they are known to science. For this reason, we 

 must consider all the classifications of birds up to the present time 

 as being merely provisional, in as much as we are yet so far from 

 possessing the necessary knowledge to define the true one, based 

 upon the complete biological history of the Class. A study of the 

 various classificatory schemes that have been presented within the 

 last twenty-three centuries will convince any one that there has been 

 just as much of an evolution in this field as there has been in the case 



