72 CICONIIFORMES : PHAETHONTIDAE chap. 



mentioned, except in some members of Phcdacrocorax. The V-shaped 

 furcula ancyloses with the sternum in some of the Sub-Order, but 

 Fregata differs from all other ornithic forms in the fact that the 

 furcula also coalesces with the coracoids at its extremities, while 

 the coracoids again unite firmly with the scapula, producing an 

 almost rigid framework, considered by Professor Newton to be con- 

 nected with the power which the bird possesses of sustaining itself 

 nearly motionless in the air.-* The peculiar angular articulation 

 of the long eighth cervical vertebra in Plotus, which causes the 

 Z-shaped " kink " in the neck, must also be noticed here.^ The 

 tongue is rudimentary ; the nostrils are pervious in Fhaethon, im- 

 pervious elsewhere, being practically obliterated in adults ; the 

 syrinx is tracheo-bronchial, except in Sulci and Pelecanus, where the 

 usual muscles are entirely absent. The subcutaneous air-cells of 

 Sula are most remarkable. The newly-hatched young are blind and 

 helpless, being naked and covered with blackish skin in Sula, Plud- 

 acrocorax, Plotus, and Pelecanus, though they soon acquire a white 

 downy coat ; in Pliaethon and Fregata they are similarly clothed 

 on breaking the shell. The down of the adults is uniformly dis- 

 tributed, the after shaft is diminutive or wanting. The gular sacs, 

 horny excrescences on the beak, crests, and so forth, are noted below. 



Pam. I. Phaethontidae. — Phaiithon aetliereus,P. fiavirostris, and 

 P. rubricauda wee, chiefly found in the tropical regions of the south ; 

 but the first two species breed about as far north as the tropic 

 of Cancer, while they frequent the West Indies, and occasionally 

 stray to the Eastern United States, or even Newfoundland.^ The 

 first and third are found nesting northwards to Laysan. All these 

 Tropic- or Boatswain-birds, as they are denominated, have satin-like 

 white plumage — often with a tinge of pink — varied by blackish 

 bars or patches above, and black marks near the eye ; the bill is 

 red, or in P. fiavirostris yellow, the metatarsi yellowish and the 

 toes chiefly black. In P. rubricauda the long stiff median rectrices 

 are dull red with black shafts and very narrow webs, in P. fiaviros- 

 tris they are pinkish with similar shafts, and in P. aetliereus entirely 

 white. The sexes are alike, the young being more irregularly 

 marked and having no long tail-feathers. 



The members of this Family are true denizens of the ocean, 



' A. Newton, Did. Birds, 1893, pp. 293, 294. 



" W. A. Forbes, P.Z.S. 1882, pp. 208-212. 



' The East American form of P. fiavirostris is separated as P. americanus by 



Mr. Ogilvie Grant, SuU. Ornith. Oluh, vii. 1897, p. xxiv. 



