552 CLASS XVI. 



le halbusard, der Fluss-Adler. This species feeds on fresh- water fish, and 

 is found in Europe, Arabia, Egypt, &c. Whether the North American 

 Fish-Eagle (Falco carolinensis Gm., Wils. Am. Oni. ii., i. 103, Tab. 37, 

 fig. I, ViEiLL. Gcd. PI. II.) be specifically different, requires further 

 investigation. ScHLEGEL unites them both with Pandion leucocephalus 

 Gould, from New Holland, as one species. — Pandion humilisJ. Mueller 

 and ScHLEG., Verhand. over de nat. Gesch. der Nederl. Overzeesche bezittingen, 

 Aves, Tab. 6; Sumatra, Malacca, This species, as also another from the 

 East Indies, which according to Mueller occurs chiefly at Borneo, Fcdco 

 ichthyactus HoESF., is distinguished from Pandion haliaetus by some cha- 

 racters of structure. Conip. Mueller and Schlegel loc. cit, 



Polylorus Vieill. ( Caracara AzARA, Cuv.) Bill shorter than 

 head, compressed, curved; upper mandible with margin sinuate or 

 furnished with an obtuse, rounded tooth. Cere large; nostrils placed 

 at the anterior margin of cere near the culmen. Wings long, 

 with third, or third and fourth quills longest of all. Tail long 

 or moderate, rounded, broad. Tarsi long, reticulate, covered ante- 

 riorly with scutella in pairs, lower down above the bases of toes 

 with a sin2;le row of scutella. Toes covered in front with trans- 

 verse scutes; claws moderate, moderately curved. Region round 

 the base of bill and eyes somewhat naked, covered with scattered 

 setaceous plumes. 



Sp. Polyhorus vulgaris, Vieill., Falco brasiliensis Gm., Vieill. Gal. PI. 7; 

 very numerous in South America. 



Sub-gen. Ibycter Vieill. (and Milvago Spix). 



Sp. Polyborus aquilinus, Ibycter leucogaster Vieill., Falco aquilinus Gm., 

 Buff. PI. enl. 417, &c. All the species from South America, excejit one 

 from New Holland and other islands of the South Sea ; Polyborus leucunis, 

 Falco Icucurus Lath., Gm. ; Falco ZcelancUce Temm. PI. col. 192, 224. — 

 These birds form the transition from Circactus to the following family. 



Gypogeranus Illig., Serpentarius Cuv. Bill shorter than head, 

 curved, compressed towards the tip, hooked. Nostrils lateral, oblique, 

 almost vertical, placed at the anterior margin of cere. Orbital 

 region naked ; head closely covered with plumes. Tarsi elongate, 

 slender, more than double the length of middle toe, covered in front 

 and behind with a row of transverse scutes. Toes short, the outer 

 conjoined at the base by membrane; hallux small, resting on the 

 point only. Wings elongate, with third, fourth and fifth quills 

 subequal, longest of all. Tail graduated, with two middle feathers 

 very long. 



Sp. Gypogeranus serpentarius Illig., Falco serpentarius Gm., Serpentarius 

 reptilivorus Daud., Gray, Buff. PI. enl. 721, A. Vosmaer Bcschrijv. van 



