227 



which can only be considered a decided retrof?rade from, instead of an 

 improvement upon, the better classifications which preceded it. In the 

 first place, the genus Pandion is made to form a "suborder" — Pandlones ! 

 This would not be so bad, all things considered, were it not that the 

 geuns Polioaetus is included in this so-called "suborder", the latter 

 being a very near relative, probably a subgenus, of Haliaetus, one of 

 the group BiUeonen of the subfamily Buteonince, and not at all allied to 

 Pandion (group Pandiones of Buteonince), though it represents that genus 

 in its group ; that is, is analogous, but not affined to it. In the next 

 place, iSerpentarius (= family Serpentariidce) and Gariama {= family 

 Cariamidce) are placed in the " subfamily " PoZy&ormfC.' The subfami- 

 lies which Mr. Sharpe recognizes are the following : (1) PolyborincB, (2) 

 Accipitrince, (3) Buteonince, (4) Aquilince, and (5) Falconince. 



In this connection, it may be well to call attention to the importance 

 of distinguishing between evidences of affinity and those of mere anal- 

 ogy in the birds of this family. Certain types of teleologic«-l modifi- 

 cations are repeated in members of different subfamilies, and in different 

 groups of one subfamily, to such a degree of perfection, that, if we were 

 to follow external appearance only, we would not hesitate to place 

 them near together in a systematic arrangement. This is what has 

 led to such confusion and such utterly unsatisfactory results as have 

 characterized most attempts at a natural classification. Among the 

 more prominent instances of analogy between members of different 

 groups or subfamilies, or even different families, the following may be 

 mentioned : The family Cathartidce is reproduced in the vultures of the 

 Old World (vulturine series, group Buteones, subfamily Buteonince, fam- 

 ily Falconidce) ; the Gypogeranidce and Cariamidce, in a less degree, by 

 Polyboroides and Geranospizias {Buteones); the Strigidce, in a very slight 

 degree, by Circus {Buteones, Buteonince), Micrastur [Micrastures, Fal- 

 conince), and Pandion {Pandiones, Buteonince).* The Falcones are rep- 

 resented in the Buteonince by Ictinia and Harpagus [Buteones)', also 

 by Baza (Pernes) ; one of thePolybori (Ihycter) by BostrJianius (Buteones) ; 

 the Micrastures are repeated in the genera Circus and Nisus t [Buteones), 

 and Serpetotheres very nearly imitated by Circaetus [Buteones). Taking 

 the Buteonince alone, the Pandiones are mimicked by certain Haliaeti 

 [Buteones) ; Certain Pernes [Elanoides) by Milvus and Nauclerus [Buteones) ; 

 and others of the same group [Baza and Aviceda) by Harpagus and 

 Ictinia. 



In three widely-distinct " series " of genera in the group Buteones, we 

 find a very peculiar type of modification, viz, the excessive abbreviation 

 of the outer toe. This occurs only in Heteropus (an " aquiline "form, 

 with densely-feathered tarsus), Polyboroides (a long-legged terrestrial 

 form, with reticulated tarsus), and Geranorpozias (similar to the last, but 

 with scutelate tarsus) ; these latter two differ from the first in being 

 of terrestrial habits, and in a very remarkable teleological modification 

 of the tibio-tarsal joint, whereby it can be bent with ease in both direc- 

 tions. 



The following tabular arrangement expresses the equivalents of the 

 two subfamilies and several groups, adopted in this memoir in the 

 numerous " subfamilies," or " families " of leading authorities, and suc- 



* Circus resembles the owls merely in the possession of a distinct facial ruff and large ear- 

 aperture; Micrastur, in the same respects, and also in decomposed downy edges to the 

 inner webs of the primaries, the rounded, concave wing, as well as in the dimorphic plum- 

 age of some ot the species (" rufescent" and "gray" "phases"); Pandion, in having 

 the outer toe reversible and in lacking after-shafts to the feathers. 



t In general form, Micrastur exactly repeats the genus Nisus, and has, besides, the facial 

 ruff of the genus Circus. 



