174 CALIFORNIA ACADEMY OF SCIENCES. 



cause strongly marked hybrid feathers form both the 

 upper and the lower line of the patch. The upper line 

 is formed by white feathers with the distal half sharply 

 black, and the lower edge by black feathers with the 

 distal end edged with white. This is rather unusual, 

 for the rule is that when the base and tip of a feather 

 are differently colored on one side of a patch they pre- 

 serve the same relative positions upon the other side. 



In order to study these hybrid feathers more system- 

 atically I shall make the following classification: 



I. Hybrids (feathers of two or more colors helping 

 to define a patch). 



1. Symmetrical. 



a. Lateral. 



rp f Relative positions uniform. 



b. Transverse < .... , , 



I Relative position interchangeable 



2. Asymmetrical. 



a. Sharply marked. 



b. Indistinctly defined. 



II. Pseudohybrids (feathers of two or more colors 

 not helping to define a patch). 



1. Sharply marked. 



a. Both colors showing. 



b. Only one color showing, the other concealed. 



2. Tinged with some foreign color. 



I will now explain each of these divisions and give 

 examples. I have restricted the term hybrid feathers to 

 such as are divided into two or more parts by color and 

 in which* each color shows in the general pattern of the 

 bird. Where two colors show in a feather but have no 

 significance in defining a patch, I 'have termed them 

 pseudohybrids. In a large proportion of cases patches 

 of color are marked on one side at least by true hybrid 

 feathers. When the feathers are divided into two toler- 

 ably uniform parts they may be considered as sym- 



