152 CHAPMAN, String Moult of the Bobolink. reall 
Dr. Chadbourne has examined this Corumbé specimen, but his 
conclusions differ from my own. In brief, he says that the moult 
is not a complete one, but that certain feathers of the winter 
plumage have changed to the color of the breeding plumage, and 
that in the white area of the abdomen there are some white 
feathers not fully mature. He further says: “*My Bobolink 
showed none of this white marking on the breast or abdomen, nor 
did it have the chestnut shading, which is so prominent in the 
Corumbaé specimen, and Dr. Allen says nothing of any similar 
coloring among the birds seen by him. When we call to mind 
the fact, to be referred to later, — that the black of the Bobolink is 
really due to brown, instead of black coloring matter, — it is at 
once clear that the excess of chestnut and white show a lack of 
the normal quantity of pigmented matter; and it seems almost 
sure that in the Corumba bird, we have not a normal example, 
but a partial albino!” 
In attempting to explain the reasons for this difference in Dr. 
Chadbourne’s opinion and my own, let us first consider the 
question of change in the color of an old feather (figure 1 of the 
plate accompanying his paper). The plumage of the Reedbird, 
especially of adult specimens, often contains black feathers, the 
terminal yellow tips of which show them to be new. Dr. 
Chadbourne figures such a feather in his plate (fig. 1). What 
becomes of these feathers? In an adult male taken September 
25, in Jamaica, W. I. (Am. Mus. No. 42134) nearly all the 
feathers of the breast and sides are so marked. ‘The bird could 
not well lose them without these parts becoming featherless. There 
is no reason to doubt, therefore, that they are retained until the 
spring moult, and in my opinion it is on one of these black 
feathers that Dr. Chadbourne bases his statement of spring 
color change without moult of the feather in the Corumbaé 
specimen, when in truth there is no evidence whatever to show 
that this feather was not black when it was acquired at the 
preceding moult. 
As to the “not fully mature feathers’ which Dr. Chadbourne 
reports finding in the white area on the lower breast and abdo- 
men of the Corumbé bird, one of which he figures (fig. 2), I 
must confess that after .the most careful search I have failed to 
