BIRDS OF NORTH AND MIDDLE AMERICA 525 



ridge; mandible without ramal vacuity; nasal bones very incompletely 

 ossified, the nostril opening so as to fully expose the nasal septum and 

 not enclosing a central bony tubercle; procoracoid small, articulating 

 with scapula only, and widely separated from clavicle; thoracic ver- 

 tebrae all free; no gap between fu-st and second bronchial semirings; 

 egg-shells with green translucence. 



The Pandionidae are a small group of piscivorous diurnal "bhds of 

 prey" which differ externally from all others in their long, strongly 

 curved and acute claws, which are not only of equal length (not gradu- 

 ated in size from that of the hallux, the largest, to that of the outer 

 toe, the smallest) but instead of being broad and concave or 

 grooved beneath are narrower, smooth, and rounded (in transverse 

 section) on their under surface; in the heavy and peculiarly scaled 

 tarsi, and the short, dense feathering of the thighs. The group is 

 represented by a single, apparently monotypic, genus of nearly cos- 

 mopolitan range, though wanting in very cold regions. The ospreys 

 feed exclusively on fishes and therefore frequent the larger rivers, 

 lakes, and seashores. 



Genus PANDION Savigny 



Pandion Savigny, Descr. Egypte, livr. 1, i, 1809, 69, 95. (Type, by monotypy, 

 P. fluvialis Savigny = /^a^co haliacius Linnaeus.) 



Pandiun (typog. error) Lembeye, Mem. Real. Soc. Econ. Habana, ser. 2, vi, 

 No. 5, 1849, 332. 



Triorches Leach, Syst. Cat. Mam. Birds Brit. Mus., 1816, 10. (Type, by mono- 

 typy, T. fiuviales Leach = /^a/co haliaetus Linnaeus.) 



Balbusardus Fleming, Hist. Brit. Anim., 1828, 51. (New name for Pandion 

 Savigny.) 



Balbuzardus (emendation) Rey, Syn. Eur. Brutvogel und Gaste, 1872, 172. 



Ichthyaetus (not Ichthyiaetus Kaup, 1829) Sweeting, in N. Wood's Naturalist, 

 ii, No. 12, Sept., 1837, 303. {Type, I. piscivorusSweetmg=Falco haliaetus 

 Linnaeus.) 



Bill about half as long as head, the culmen somewhat arched basally 

 and very strongly decurved, the tip of the maxilla produced into a 

 relatively long and narrow unguis, the maxilla somewhat inflated 

 laterally, its tomium sinuated (more or less convex in or slightly an- 

 terior to middle portion, more or less concave posteriorly) ; gonys 

 shghtly convex or nearly straight, ascending terminally, rather prom- 

 inent basally through narrowing of mandibular rami; mandibular 

 tomium strongly convex or arched, faintly notched or incised sub- 

 terminally; cere rather narrow, its upper outline depressed more or 

 less below level of highest point of culmen, its anterior outline nearly 

 vertical for upper half (but slightly receding across base of culmen, 

 where forming a slight concavity), then gradually receding below 

 toward rictus; nostril obhque (its upper end the anterior one), narrow 

 (almost sUtlike) anteriorly beveled off to edge of cere, its posterior 



