TEE TROPIC SEA BIRDS. 349 



and much curved, its toes nearly of equal length, and capa- 

 ble of being applied in the most effectual manner, in pairs, 

 two and two opposite each other. It must also possess con- 

 siderable power, and therefore its legs are strong and mus- 

 cular, and to prevent its being inextricably entangled the 

 claws are smooth and rounded, so that they can, if necessary, 

 be readily withdrawn. The animals on which it feeds live 

 in the water, ordinarily beyond its reach, coming occasionally 

 to the surface; the bird, therefore, has a comparatively 

 slender form, with very long wings, so as to enable it to 

 remain without fatigue sailing or hovering over the water 

 until an opportunity of pouncing occurs. To prevent its 

 plumage from being injured by its sudden immersion into 

 the water, the feathers of the lower surface are rather more 

 compact and considerably shorter than in eagles and most 

 other birds of tlie family, and those of the leg are short all 

 round, while most other species have a large tuft of short 

 feathers. The structure of the wings is also curious : in the 

 osprey they are very long, yet length is not of itself an 

 indication of great speed so much as the power of easy sus- 

 pension in the air and of continued flight. The osprey re- 

 quires to hover long over the waters, often over the open 

 sea at some distance from land, sometimes for hours together 

 before an opportunity for pouncing on its prey occurs. Its 

 form, therefore, is as light as is compatible with strength. 



"True to the season, o'er our sea-beat shore. 

 The sailing osprey high is seen to soar, 

 With broad unmoving wing, and circling slow, 

 Marks each loose straggler in tlie deep below — 

 Sweeps down like lightning, plunges with a roar. 

 And bears his struggling victim to the shore." 



We have now to notice another family, the Phaeton or 

 Tropic Birds, so named because, from their habitual residence 

 under the burning zone, bounded by the tropics, they seem 



