390 University of California Publications in Zoology  {Vou.18 
4, The Phylogenesis of Birds as Modified by Morphology of Feathers 
As intimated above, distinct lines of evolution in the modification 
of the structure of feathers are clearly shown by this study. After 
making a careful analysis of these various lines of divergence, which 
seem to be more or less orthogenetic in nature, a phylogenetic tree 
representing the evolution of birds has been worked out, and is pre- 
sented in fig. G (p. 391). In so far as it is in accord with the facts of 
morphology of the feathers, the classification presented by Knowlton 
(1909) has been adhered to in the preparation of this evolutionary 
tree, since it is believed that this classification is most nearly in 
accord with the views of most of the leading ornithologists of the 
present time, and most nearly embodies the evidence furnished by 
recent work on comparative avian anatomy and morphology. In 
all eases in which the evidence furnished by morphology of feathers 
is distinctly not in accord with Knowlton’s interpretation of rela- 
tionship, the classification has been altered so as to agree with the 
facts of epiphyology presented in this paper. The phylogenesis 
presented, therefore, is one which is based primarily on morphology 
of feathers, but in which the system presented by Knowlton (1909) 
has been adhered to in so far as there was no conflict. While it 
is not supposed that such an interpretation of relationship is neces- 
sarily the correct one, or that some other interpretation may not 
be made which will better satisfy all the conditions of avian struc- 
ture, it is hoped that the accompanying phylogenetic tree will be 
of use to taxonomists in the embodiment of the facts presented in 
this paper in the preparation of a system of classification which 
will best satisfy the conditions of all branches of the comparative 
morphology of birds. 
Transmitted April 17, 1914. 
