846 THE AMERICAX XAn-RALIST. [Vol. XXXVIII. 



have them furnish the requisite data uix)n which the hnear 

 scheme of this classification has been based. Without any man- 

 ner of doubt this is the most elaborate provisional scheme of 

 the classification of Birds extant, and beyond all question, in 

 most particulars, the relationships of the groups as therein rep- 

 resented are correct, and, as far as possible, convey to our minds 

 wIkU has taken place in their evolution. 



In settin.i; forth a scheme of classification, the principal objec- 

 tion to the linear method is that it does not properly represent 

 the branching or the derivation of new groups in time as the 

 taxonomer has them in his mind. It brings some groups too 

 close together, throws others too far apart, and in some instances 

 in the hneal descent interpolates groups among others in such a 

 way as to either do violence or misrepresent the true affinities 

 antl relationships of the forms as they exist or have existed in 

 nature. Hy the employment of the phylogenetic tree we obviate 

 a -reat many of these objectionable features so dangerous to 

 the credit of a natural classihcation. Still notwithstanding all 

 this, the linear method has been adopted in the present memoir, 

 and for the reason that it is believed that the time is not yet at 

 hand again, when the makmg ,,f another elaborate phylogenetic 

 tree for birds would be considered justifiable as we are still in 

 the provisional stage. Therefore it has been adopted here. 

 I'urther, it has been thought better to weave into this scheme 

 such fossils of extinct types and s})eeies of birds as have come to 



been influenced in the classitication here set forth bv my having 



studied exerything that pertains to birds for a period extending 

 over thn ty yeais. This study has been constant, and has been 

 undertaken \\\ the tield, in the closet and in the dissecting room- 



department of ornithology and 



u'se studies have been supplemented by similar studies m 

 structure and habits of manv mammals, reptiles, batrachians. 



