NATURAL SCIENCES OP PHILADELPHIA. 143 



Subfamily HA LIME TIN* E. 



No membrane between the toes, which are instead cleft to the base. 

 Genus HALLEETUS, Savigny. 



Bill very large, inflated; chord of the admen more than twice the length of the 

 cert on top: commissure only slightly sinuated. Nostril elongate-oval' ob- 

 liquely vertical. Toes and posterior face of tarsus with transverse scut, 

 posterior face of tarsus with circular plates. 1st quill shorter than 7th ; 2i\ 

 to 6th (inclusive) sinuated on outer webs; inner webs of outer six deeply 

 emarginated. 



1. 4th quill longest; tail slightly rounded. 



//. leucocephalus, (Briss.) Savig. 



2. 3d quill longest; tail very much graduated, or cuueate. 



II pelagicut* 

 II. No bare, projecting, superciliary shield. 



Middle toe longer than naked portion of tarsus in front. 



Subfamily MIL VINE. 



Closely feathered above, and generally all round, the eye. Feet very robust 

 and strong; tarsus usually short; the naked portion in front less - : 

 length of the middle toe; toes cleft to the base, or else the membrane between 

 outer and middle toe not well developed. Wing very long. Tail variable, 

 being slightly rounded, square, emarginated or excessively forked. Bill black 

 or dusky. f 



A. Tarsus without transverse scutelhc. 



a. Claws not grooved beneath, the lower surface being rounded, or just per- 

 ceptibly flattened-. 



Genus PANDION, Savigny. 



Bill inflated, the cere depressed below the arched culmen ; end of bill much 

 developed, forming a strong, pendant hook. Anterior edge of nostril touching 

 edge of the cere. Whole of tarsus and toes (except terminal joint) covered with 

 rough, somewhat imbricated, projecting scales Outer toe. versatile; all the 

 claws of equal length ;| in their shape also they are peculiar ; they contract 

 in thickness to their lower side, where they are much narrower than on top, 

 as well as perfectly smooth and rounded; the middle claw has the usual 

 sharp lateral ridge, but it is not very distinct. All the toes perfectly free. 

 Tibia not plumed, but covered compactly with short feathers, these read 

 down the front of the tarsus below the knee, and terminating in an an 

 Primary coverts hard, stiff-and acuminate, almost as much so as the quill? th< ra- 

 selves : 3d quill longest; 1st longer than 5th; 2d, 3d and 4th sinuated on 

 outer webs ; outer three deeply emarginated, the fourth sinuated, on inner 

 webs. 



P. haliaetus, (Linn.) Less., and P. Carolinentis, (Gmel ) Bonap. (= 

 liaetus var. carolinensis). 



* Aquila pelagica, Pallan, Zoog. Ross. As. I, 343. L811. Halieelus pelagicut, Zcit., : 

 Falk. Mus. Senck. 261. (Does not belong to North American fauna I 



f The light greenish or yellowish bill in all the Pnlyborinse, induces me to usi 

 parently trivial character, as a diagnostic one. The distinction between "i/i/m 

 "PolyboriniB" is by no means well marked, and there are intermediate forms 

 and 'ibycter) which almost induce me to designate them as sections oi one subfi m 

 find it difficult, if possible, to diagnose them separately by anything more than meiely 

 comparative characters. , . 



1 No other Raptorial bird that I have seen hares with Pattdion m this cnriou 

 Indeed, most of the characters of this genus are so unique, that it is almost emit.' 

 the rank of a separate subfamily. 



1870.] 



