144 PROCEEDINGS OF THE ACADEMY OF 



Genus ELANUS, Savigny. 



Bill rather small and narrow, the tip normal ; commissure moderately sinu- 

 ated ; upper outline of lower mandible greatly arched, the height at base less 

 than half that through middle; gonys almost straight, declining downward 

 toward tip. Nostril circular, in middle of cere. Tarsus and toes (except ter- 

 minal joint) covered with small roundish scales ; under surface of claws just 

 perceptibly flattened; sharp lateral ridge on middle claw very prominent ; a very 

 slight membrane between outer and middle toes. 2d quill longest, 3d very 

 slightly shorter ; 1st just exceeding 4th ; 2d and 3d with outer webs slightly 

 sinuated ; inner web of 1st emarginated, of 2d sinuated. Tail peculiar 

 emarginated but the lateral feather much shorter than the middle, the one 

 next to it being the longest E. leucurus, (Vieill.) Bonap. 



b. Claws flattened, or slightly grooved, beneath. 



Genus NAUCLERUS, Vigors. 

 Bill as in preceding, but less deep and less compressed ; gonys straighter. 

 Nostrils oval, obliquely vertical. Toes with transverse scutellse to their base; 

 scales of tarsus large ; lower edges of claws sharp ; middle claw bent laterally, 

 the inner side much arched, the edge sharp ; a just distinguishable membrane 

 between outer and middle toes. 3d quill longest, 2d scarcely shorter; 1st 

 slightly exceeding 4th ; 2d and 3d with outer webs just perceptibly sinuated, 

 the cuttings near the end. Tail excessively forked, the latter feather more than 

 twice as long as the middle N. forflcatus* (Linn.) Ridgw. 



B. Front of tarsus with transverse scutellte. 



Genus ICTINIA, Vieillot. 

 Bill peculiar, being very short and deep, the commissure with a heavy fes- 

 toon, behind and in front of which is a more or less perceptible indentation; 

 gonys convex, ascending toward tip. Nostril very small, circular. Membrane 

 between outer and middle toes well developed. Claws short, robust, flattened 

 beneath, the edges sharp, particularly that on the inner side of the middle 

 claw, which is somewhat bent. 3d quill longest. 



1. 2d quill much longer than 4th ; outer webs of quills not sinuated ; 

 inner web of 1st emarginated, of 2d sinuated. 



/. mississippiensis, (Wils.) Gray. 



2. 2d quill much shorter than 4th; outer web of 2d and 3d sinuated 

 (near bases) ; inner web of outer three emarginated. 



/. plumbea, (Gmel.) Vieill. 



Genus ROSTRHAMUS, Lesson. 

 Bill very narrow, upper mandible much elongated and bent, the tip pro- 

 duced downward in a strong hook ; lower mandible dropping terminally, the 

 gonys perfectly straight, the upper outline much arched, to correspond witb 

 the convavity of the commissure Nostril elongate-oval, horizontal. Mem- 

 brane between outer and middle toes easily distinguishable. Claws extremely 

 long, and very sharp, though but gently curved 3d and 4th quills equal, and 

 longest; 1st = 7th ; 2d, 3d, 4th and 5th deeply sinuated on outer webs (near 

 base) ; inner webs of outer five emarginated. Tail emarginated. 



R. sociabilis, (Vieill.) D'Orb. 



Middle toe shorter than bare portion of tarsus in front. 

 Subfamily (?) POLY BORING. 

 Nostril with a bony tubercle, but of rather various form. Bill generally 



* Falcn forficatus, Linn., Syst. Nat. I, 89, 1758. Falco furcatus, I, inn., Syst. Nat. p. 129, 

 1706. Nauclerut furcatus, Vig., Zool. Journ. II, :j87. Canain, B. N. Am. 1858, 36, et Auct. 



[Dec. 



