Proceeding eastward, on the other hand, from our starting-point, we find another race, in _P. arcticus_, occupying the western slope of the Missouri Valley and the basin of the Saskatchewan, in which, on the contrary, the white increases in quantity, and more and more to its eastern limit. The black borders of the wing-patches disappear, leaving them white externally; and decided white edgings are seen for the first time at the bases of primaries, as well as near their ends, the two sometimes confluent. The terminal tail-patches are larger, the outer web of the exterior feather is entirely white except toward the very base, and we thus have the opposite extreme to _P. oregonus_. The wings are longer; the third primary longest; the first usually longer than the secondaries or the ninth quill. Finally, proceeding southward along the table-lands of Mexico, and especially on their western slope, we find _P. maculatus_ (the first described of all) colored much like the females of the more northern races, except that the head and neck are black, in decided contrast to the more olivaceous back. The wing formula and pattern of markings are much like _megalonyx_, the claws more like _arcticus_. Even in specimens of _megalonyx_, from the southern portion of its area of distribution, we find a tendency to an ashy or brownish tinge on the rump, extending more or less along the back; few, if any indeed, being uniformly black. As, however, a general expression can be given to the variations referred to, and as they have an important geographical relationship, besides a general diagnosis, we give their characters and distribution in detail. The general impression we derive from a study of the series is that the amount of white on the wing and elsewhere decreases from the Missouri River to the Pacific, exhibiting its minimum in Oregon and Washington, precisely as in the small black Woodpeckers; that in the Great Basin the size of the claws and the length of tail increases considerably; that the northern forms are entirely black, and the more southern brown or olivaceous, except on the head. The following synopsis will be found to express the principal characteristics of the species and their varieties, premising that _P. arcticus_ is more distinctly definable than any of the others. We add the character of the green-bodied Mexican species to complete the series. Synopsis of Varieties. I. _P. erythrophthalmus._ 1. Wing, 3.65; tail, 4.20. Outer tail-feather with terminal half of inner web white. Iris bright red, sometimes paler. _Hab._ Eastern Province United States. (Florida in winter.) var. _erythrophthalmus_. 2. Wing, 2.90; tail, 3.75. Outer tail-feather with only terminal fourth of inner web white. Iris white. _Hab._ Florida (resident) var. _alleni_. II. _P. maculatus._ A. Interscapulars with white streaks.