In the Birds of North America, the specimen characterized on p. 637 of the present work as _æstivalis_, var. _arizonæ_, was referred to _P. cassini_, those specimens which are here retained as such being considered as in quite immature plumage. A more recent examination of additional material, however, has compelled us to change our view. In consequence of the similarity of the specimen in question to _æstivalis_, as noted in the article referred to above, the general acceptation of the name _cassini_ has been that of a term designating a variety of the common species; but we have as the result of the investigation in question found it necessary to retain under the head of “_cassini_” only the typical specimens from the Rio Grande region, and refer the supposed aberrant specimen to _æstivalis_. In this Los Nogales specimen we find existing such differences in proportions and colors as are sufficient to warrant our bestowing upon it a new name, and establishing it as the Middle Province race of _æstivalis_, in this way connecting the South Atlantic and Mexican races (var. _æstivalis_ and var. _botterii_) by a more similar form than the _P. cassini_, which must be set apart as an independent form,—in all probability a good species. Several facts are favorable to this view. First, we have of the _P. cassini_ specimens which are beyond question in perfect adult plumage, and others which are undoubtedly immature; they differ from each other only in such respects as would be expected, and agree substantially in other characters, by which they are distinguished from the different styles of _æstivalis_. Secondly, the region to be filled by a peculiar race of _æstivalis_ is represented by the var. _arizonæ_, which is undoubtedly referable to that species; thus we have in one province these two different forms, which therefore are probably distinct. The present bird is hardly less distinct from the races of _æstivalis_ than is _ruficeps_; and we would be as willing to consider all the definable forms presented in the synopsis as varieties of a single species, as to refer the present bird to _æstivalis_. HABITS. This Finch, in its general appearance, as well as in respect to habits, nesting, and eggs, is quite similar to Bachman’s Finch. It was first met with by Dr. Woodhouse, in the expedition to the Zuñi River, when he found it in Western Texas. He shot it on the prairies near San Antonio, on the 25th of April, 1851, mistaking it for _Passerculus savanna_, which, in its habits, it seemed to him very much to resemble, but upon examination it was found to be totally distinct.