62 
BULLETIN OF THE NUTTALL 
These exceptions we are unable to explain, but even unaccounted 
for they do not detract from the high importance of the variations 
we have noted. It will also be observed that there is no essential 
difference in dimensions or proportions between Folyhorus lutosus 
and P. clieriway, the modifications being almost entirely in the 
plumage, which in the former species is so distinct, at all ages, 
from that of the other in corresponding stages that it may be re- 
garded as one of the most completely differentiated birds of the 
whole series. 
Not only in proportions, but also in colors, do the modifications 
presented by these Guadalupe birds correlate with characteristics 
of the Galapagoan forms. A conspicuous character of the latter is 
their sombre plumage of black or fuliginous-brown ; now, excepting 
only Folyhorus lutosus, precisely the difference in plumage of the 
Guadalupe birds from their Continental allies consists in their 
darker colors. Garpodacus ampins, although a bird of at least double 
the bulk of G. frontalis) is so nearly identical in plumage that 
positively the only difference consists in the slightly darker shade 
of all the colors ; Junco insularis is darker than J. annectens, but is 
otherwise similar in plumage ; Fegidus ohscurus is much darker 
than R. ccdendida ; Thryomanes hrevicauda and Salpinctes guada- 
lupensis are likewise darker in colors than T. hewicki and S. ohsoletus, 
w^hile Golaptes rufipileus differs from G. mexicanus in having one 
half more black on the under side of the tail, besides being darker 
generally. In Pipilo consohrinus, however, the black portions of the 
plumage are hardly so intense black as in the mainland forms of 
F. macidatus, hut the female is almost if not quite as hlack as the 
male,^ while in the others she is more or less conspicuously differ- 
ent, being some shade of brown or gray instead of black. As 
remarked before, the only real exception to the rule is Folyhorus 
lutosus, but this has a quite different distribution of colors from 
the two Continental species; it may be observed, however, that 
while the black markings are replaced by dark brown, the lighter 
markings are pale clay-color instead of white ; and further, that 
there is far less difference between the young and adult stages. 
Not the least interesting fact concerning these Guadalupe birds 
^ The similarity of the sexes in birds having a black plumage is remark- 
ably prevalent among the West India birds, as Professor Baird has somewhere 
noted. 
