^°^'l9^?^T Phillips, The American Black Ducks. 299 



of green, while the general color of the under parts is mottled 

 instead of streaked. The light color of the m-argins of the tail 

 feathers is said to be different, as are the lighter parts of the 

 plumage in general. 



As to the color of the cheeks there is no difference in the markings 

 themselves, or in the ground color. It is true that in specimen 

 No. 4562, M. C. Z., from Brownsville the ground color of the chin 

 is rather darker than any Florida specimens which I have seen. 

 The bird as a whole is very dark, having the appearance of being 

 stained during life. As to the speculum color it varies so much, 

 as was shown above that I cannot consider it very seriously. In 

 Mr. Brewster's specimens from Texas the color was purplish green, 

 and in the other specimens there was quite a range of shading from 

 purplish green to a nearly pure purple. The direction of the light, 

 must of course be taken into consideration in judging speculum 

 colors. As to the general color of the under parts it would seem 

 that an adult male Texan bird was being compared by Sennett with 

 a female or immature male from Florida. The general color of 

 the feather margins does not show any difference in the two 

 regions. As to size, over 70 separate measurements have been 

 carefully taken and averaged, and they show absolutely no differ- 

 ence. They do show this, however, that the Florida and Texas 

 birds differ slightly from A. diazi. The culmen in A. diazi is 

 shorter, while the tarsus and wing are slightly longer. A somewhat 

 careful consideration, then, has given no proof of two races of A. 

 fulvigula. 



Anas tristis — Black Duck. 



It is not the purpose of this paper to discuss the question of two 

 forms of this species.^ Neither material nor experimental proof 

 is at hand. It is, however, very interesting to look at a mixed 

 series of A. tristis and compare it in a general way with A. diazi 

 or A. fulvigula. In the former species there is a diversity in general 

 shade and markings, especially on the lower parts, which is very 

 curious in such stable birds as the Anatidae. It suggests that we 

 are dealing with a 'mixed population', the term being used here 



^ A. rubripes and A. rubripes tristis. 



