454 R. Ridgway—Relation between Color and 
tT. LV.—On the relation between Color and Geographical Dis- 
tribution in Birds, as exhibited in Melanism and Hyperchrom- 
ism; by RoBERT Rip@way. ; 
THE two chief modifications of color experienced in the sev- 
eral geographical, or climatic, regions of the North American 
continent, by certain species of birds which are resident over a 
very extended area, are the following :—I. A melanistic tendency, 
which may be either an increase in the intensity of color or in 
the extent, of the black parts of the plumage; and Ik A greater 
brightness, or an increased prevalence, of the three primary colors, 
red, blue, and yellow. “hie 
These features are mainly noticeable as the result of a ee 
i 1a.die 
increasing as we trace a species southward. j 
These generalizations may be best illustrated by presenting 
the following especially noteworthy cases: 3 
IL Melanism triking example in illustration of this law 
is found in Chrysomitris psaltria, under which we range as races, 
. Arizone Coues, C. Mexicana Swains., and C Columbiana 
Lafr. Specimens of this bird from the southern ortion of 
the Western province of the United States (Rocky Mountains 
to California, its northern limit being about the parallel of 40°), 
have the black of the upper parts confined to the head, wings 
and tail, the entire dorsal region being olive-green; this form 
na, New Mexico, and the northern provinces of _— 
(var. Arizone),t have this olive-green clouded, or mixed, wi 
* CHRYSOMITRIS PSALTRIA Var. PSALTRIA. tthe 
_ Fringilla psaltria Say, Long’s Exp., ii, 1823, 40.—Chrysomitris psaltria Bonap- 
List, 1838.—Baird, B. N. Am., 1858, 422. : 
Hab. Rocky Mts. and Middle province of U. S., north to about 40°. 
+ CHRYSOMITRIS PSALTRIA var. ARIZONZ. : 366.— 
‘Chrysomitris Mexicana var. Arizone Coues, P. A. N. 8, Philad., 1 
Cooper, Orn. Cal., i, 1870,170. 
Hab. ‘Southern border of U. 8., in New Mexico and Arizona. 
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