42 FALCONIDA. 
arrangement of the Falconide (1875); but by incorporating some of Mr. Ridgway’s 
conclusions, this concordance is made closer. 
We have, following Dr. Coues, already removed Pandion from this family. We 
now further modify our plan by using the curious character of the relative positions 
of the distal ends of the coracoid, scapular, and clavicle, first indicated by Huxley and 
subsequently brought into prominence by My. Ridgway, to separate Micrastur from the 
Accipitrine, and place it in a separate subfamily next Herpetotheres, and near the 
Falconine and the Polyborine. We also merge the Buteonine in the Aquiline, as 
Dr. Coues has done. 
We thus have one group (A) consisting of four subfamilies, viz. Circine, Accipitrine, 
Aquiline, and Milvine, in which the scapular process of the coracoid does not meet 
the end of the clavicle, and another (B) also containing four subfamilies, viz. Herpeto- 
therine, Micrasturine, Falconine, and Polyborine, in which the scapular process of 
the coracoid meets the end of the clavicle. 
These eight subfamilies are represented in our region by thirty-three genera and about 
sixty-four species, a very large proportion of the genera and species of the Falconide 
of the world. Of the genera eight are widely spread and extend beyond the limits of 
America, seven are found in North as well as South America, and eighteen belong only 
to Mexico and Central America and the southern continent. The Falconide, therefore, 
of our region, as regards their genera, are much more nearly allied to those of South 
America than they are to those of North America; and as regards the species this 
relationship is more clearly shown, a large proportion of them being identical in the 
two regions. 
Group A. 
Subfam. CIRCINAL. 
This subfamily includes the Harriers (Circus) only, a compact group of birds with 
marked characteristics, of which the most evident is the disc or ruff which surrounds 
the face, as in the Owls. The members of the genus Micrastur also have this feature 
to a less extent, but they, again, are separated by the arrangement of the ends of the 
coracoid, scapular, and clavicle mentioned above. 
CIRCUS. 
Circus, Lacépéde, Mém. de I’Inst. iii. p. 506 (1806) ; Sharpe, Cat. Birds Brit. Mus. i. p. 50. 
A genus of very wide distribution, containing about fifteen species. These are spread 
over the temperate and tropical portions of all the larger land-areas of the world. In 
North America Circus hudsonius is the only species, and this, as shown below, ranges in 
winter as far south as the Isthmus of Panama. In South America two species occur. 
The sexes in Circus hudsonius are very distinct in coloration, the male being a 
