PHALACMOCOBACIBJE : COBMOBANTS. 731 



OS uiidnatum, a peculiar skull-bone occurring in nearly aU the petrels, the turacous {Musopha- 

 gidm), and many cuckoos; and here only the stomach develops no pyloric cavity. Cuica 2, 

 but very small. Sternum very broad for its length, the furculum firmly anchylosed, the poste- 

 rior border entire. The femoro-caudal and ambiens are present ; the accessory femoro-caudal, 

 semitendinosus, and its accessory are absent. 



The frigates are maritime and pelagic birds of most warm parts of the globe. Their 

 general contour is unique among water-birds, in the immense length and sweep of the wings, 

 length of the forked tail and extreme smallness of the feet. In command of wing they are 

 unsurpassed, and but few birds approach them in this respect. They are more nearly 

 independent of land than any other birds excepting albatrosses and petrels, being often seen 

 hundreds of miles at sea, and delight to soar at an astonishing elevation. They cannot 

 dive, and scarcely swim or walk ; food is procured by dashing dowu on wing with unerring 

 aim, and by harassing gulls, terns, and other less active or weaker birds until they are forced 

 to disgorge or drop their prey. Their habit is gregarious, especially during the breecUng 

 season, when thousands congregate to nest in low 

 thick bushes by the water's edge. The nest is a 

 shallow flat structure of sticks; the eggs, two or 

 three in number, are greenish-white with a thick 

 smooth shell. " The young are covered with yel- 

 lowish-white down, and look at first as if they had 

 no feet. They are fed by regurgitation, but gi'ow 

 tardily, and do not leave the nest until they are able 

 to follow their parents on wing." The following is 

 the principal if not the only species. 

 305. TACHY'PETES. (Gr. TaxvireTrj^, tachupetes, fly- 

 ing rapidly.) Frigates. Character as above. 

 761. T. a'quilus. (Lat. aqvilus, dark, swarthy. Figs. 



507, 508.) FkictAte. Man-of-war Bird. ^ Fig. eos. — Guiar pouch of Frigate, 



brownish-black, glossed with green or purplish, duller on the belly, wings showing bro\vn 

 and gray; ? with white on neck and breast. Length about 3.50 feet; extent 7.00-S.OO ; 

 wing 2,00; tail 1.50 ; bill 5 or 6 inches; tarsi 1 inch or less! S. Atlantic and Gulf Coast. 

 Eggs 2-3, 2.90 X 2.00. 



58. Family PHAETHONTID^ : Tropic Birds. 

 Bill about as long as the head, stout, straight, compressed, tapering, acute, paragnathous. 

 Gular sac rudimentary, almost completely feathered. Nostrils small, linear, but remaining 

 patulous. Tail with the two middle feathers in the adult filamentous and extraordinarily 

 prolonged, the rest short and broad. Among anatomical characters it is to be noted that the 

 muscles of the leg are as in Laridce, as might be expected from the outward resemblance of 

 these birds to terns ; they having the accessory semitendinosus, lacking in other famiUes of 

 the order. 



The tropic bird resembles a large stout tern in general figure ; the bill, especiaUy, being 

 almost exactly like that of a tern. The principal external peculiarity is the development 

 of the middle tail-feathers ; the feathering of the gular sac and the permanent patulance of 

 the nostrils are other features. They are graceful birds on the wing, capable of protracted 

 flight, venturing far from land. They are gregarious at all times, and nest in communities 

 along coasts and on islands, in rocky places or among low trees and bushes. As implied in 

 their name, they are birds of the torrid zone, though in their extensive wanderings they visit 

 Southern seas, and have even been reported from beyond latitude 49° N. There are but three 

 well- determined species : P. ftavirostris, P. cethereus, and P. rubricauda. 



