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 Folyhor-us lutosus 

 and P. cheriway, 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 ditferentiated birds of the 

 whole series. 



Not only in proportions, but also in colors, do the modifications 

 pi'esented by these Guadalupe bii'ds 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 Poli/horus lutosus, precisely the difference in plumage of the 

 Guadalupe birds from their Continental allies consists in their 

 darher colors. Carpodacus ampins, altliough a bird of at least double 

 the bulk of C. 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 ; Begidus obscurus is much darker 

 than R. calendula; Thryomanes brevicauda and Salpinctes guada- 

 lupensis are likewise darker in colors than T. hewicki and S. obsoletus, 

 while Colaptes rufipileus diff'ers from- C. mexicanus in having one 

 half more black on the under side of the tail, besides being darker 

 generally. In Pipilo consobrinus, however, the black portions of the 

 plumage are hardly so intense black as in the mainland forms of 

 P. maculatus, but the female is almost if not quite as blach 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 Polyborus 

 lutosus, but this has a quite different distribution of colors from 

 the two Continental species; it may be obsei'ved, 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 diff'erence 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. 



