In regard to the song-sparrow (_Melospiza_), Coues writes: “The type of the genus is the familiar and beloved song-sparrow, a bird of constant characters in the east, but in the west is split into numerous geographical races, some of them looking so different from typical _fasciata_ that they have been considered as distinct species, and even placed in other genera. This differentiation affects not only their color, but the size, relative proportions of parts, and particularly the shape of the bill; and it is sometimes so great, as in the case of _M. cinerea_, that less dissimilar looking birds are commonly assigned to different genera. Nevertheless the gradation is complete, and affected by imperceptible degrees.... The several degrees of likeness and unlikeness may be thrown into true relief better by some such expressions as the following, than by formal antithetical phrases: (1) The common eastern bird commonly modified in the interior into the duller colored (2) _fallax_. This in the Pacific watershed, more decidedly modified by deeper coloration,—broader black streaks in (3) _hermanni_, with its diminutive local race (4) _samuelis_, and more ruddy shades in (5) _guttata_ northward, increasing in intensity with increased size in (6) _rafina_. Then the remarkable (7) _cinerea_, insulated much further apart than any of the others. A former American school would probably have made four ‘good species,’ (1) _fasciata_, (2) _samuelis_, (3) _rafina_, (4) _cinerea_.” Somewhat similar relations are found in three other genera of finches. Thus Passerella is “imperfectly differentiated”; Junco is represented by one eastern species, but in the west the stock splits up into numerous forms, “all of which intergrade with each other and with the eastern bird. Almost all late writers have taken a hand at Junco, shuffling them about in the vain attempt to decide which are ‘species’ and which ‘varieties.’ All are either or both, as we may elect to consider them.” In the distribution of the genus Pipilo similar relations are found. There is an eastern form much more distinct from the western forms than these are from each other.