A specimen from Paraguay (58,738, ♂ ? Capt. T. J. Page, U. S. N.) has the slaty above lighter than in the Mirador male, approaching to ash. The white bars on the black side-patches are very numerous and regular; the white of the forehead is more sharply defined, and the deep rufescent-ochre of the posterior portion of the postocular stripe is even deeper than that of the tibiæ, etc.; the breast has a few narrow blackish streaks. The bars on wings and tail, however, are as in Mexican examples. This specimen probably denotes greater age than any other in the series. Another specimen (29,809, ♀, Mirador), perhaps very young, is rather different from the others in the coloration of the lower parts; the rufous of the posterior portions is very deep, and the anterior light places are much tinged with ochraceous, the supraloral stripe being tinged throughout with the same; across the breast is a series of small tear-shaped spots of black, forming an imperfect band; there are, however, no other differences. Nos. 29,520 (♀, Chile, Berlin Museum) and 29,521 (♂, Venezuela) differ from the rest only in a deeper tinge of ochraceous anteriorly beneath, the occipital stripes being very red. No. 18,497 (♂, from the Rio Pecos, Texas) is in the plumage described as that of the young male, having the rusty tinge on rump, and more numerous bands on tail; the breast is almost as deeply ochraceous as the tibiæ, and the broad black patches of the sides scarcely meet across the abdomen, being there broken into streaks. [Illustration: _Falco femoralis._] A female, nearly adult, from Buenos Ayres (45,692, Conchitas; W. H. Hudson), has the feathers of the upper parts faintly edged with white; the rump and upper tail-coverts conspicuously barred with the same. The head above is decidedly more bluish than in northern examples, each feather with a shaft-line of black. The tail has only seven white bars,—these, however, very sharply defined, and very pure white; the longest primary has eleven white bars. The lower plumage is similar to that of the immature male from the Rio Pecos, Texas (No. 18,497). This specimen has the second and third quills equal. LIST OF SPECIMENS EXAMINED. National Museum, 14; Boston Society, 5; Philadelphia Academy, 2; New York Museum, 1; G. N. Lawrence, 1; R. Ridgway, 2. Total, 25. _Measurements._ +----+-----------+-----------+---------+---------+-----------+----------+ |Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.| +----+-----------+-----------+---------+---------+-----------+----------+ | ♂ | 9.20–10.70| 6.30–8.00| .60–.68|1.70–1.85| 1.35–1.50| 12 | +----+-----------+-----------+---------+---------+-----------+----------+ | ♀ |11.00–11.60| 7.80–8.80| .71–.80|1.80–2.00| 1.55–1.70| 9 | +----+-----------+-----------+---------+---------+-----------+----------+