RHYNCHOPIDyE — TIIP] SKIMMERS — IlIlYNCnOPS. 198 



the same. Basal half" (approximately) of the bill l)iiji;ht vermilion, the inandihle more scarlet, 

 shading into yellowish on the tomiiun ; terminal portion black ; iris (huk brown ; legs and feet 

 rich orange-vermilion, claws black. Adult, in winter: Similar, but the Ijlack more brownish, and 

 interrupted by a broad nuchal collar of white. Young, jvrst plumage : Upper parts light buff, each 

 feather with a central spot of black, these spots largest on the scapulars ; lores and sub(jrbital 

 region uniform pale buff ; a space immediately before and behind the eyes, dusky. Greater wing- 



coverts slate-black, tipped with white ; secondaries pure white for nearly the whole of the expofed 

 portion ; primaries black, the fourth, fifth, and sixth bordered terminally with light buff, the four 

 inner quills dusky, passing gradually into white at the ends. Lower parts entirely pure white. 

 Bill and fi-et reddish dusky. Downy young : Above, very pale grayish buff, irregularly and sparsely 

 mottled with blackish ; below, immaculate white. 



Adult male : Total length, about 17.00 to 20.00 inches ; extent, 48.00 ; wing, 14.75-15.75 ; tail, 

 5.50, its fork, about 1.20 ; culmen, 2.55-2.80 ; gonys, 3.40-4.70 ; tarsus, 1.30 ; mi.Idle toe, .80- 

 .85. Adult female: 15.25 to 16.75, 44.50, 13.50-14.25, 4.40-5.00, 2.00-2.30, 2.45-3.00, 1.15-1.20, 

 .75. 



As a rule, South American specimens are larger than those from North America, the bill espe- 

 cially being much longer. Thus, in a series of eight adult examples from northern localities, the 

 mandible measures from 2.90 to 4.10 inches in length (measuring from the chin), while in three 

 skins from South America, and one each from Guatemala and Nicaragua, the same measurement 

 ranges from 4.50 to 4.70 inches. In an adult male from Ccmchitas, Buenos Ayres, however, the 

 mandible is only 3.25 in length ; while in another from Peru (No. 15511 ; Captain Wilkes) it 

 measures 3.60, and is remarkably narrow. This specimen has the tail wholly uniform dusky. 

 We have not been able to discover any constant differences of coloration between northern and 

 southern birds of this species. There is much variation as regards the color of the tail, which in 

 some is wholly a uniform dusky-brown color ; in others (older birds ?) the tail is white, only the 

 intermedin being brownish, and these with a broad edging of white. Other specimens are var- 

 iously intermediate in this respect, so that this variation is probably due to age.^ Audubon 

 (" Birds of America," VII. 73) says that in the young, "after the first autumnal moult, there is on 

 the hind part of the neck a broad band of white, mottled with grayish black ; " the upper parts of 



^ According to M. Taczanowskl, in " Proc. Zool. Soc. Lend ," 1874, pp. 562, 563, Peruvian specimens 

 differ constantly in several respects from North American examples, and to such an extent tbftt he consid- 

 ers them specitically distinct. He says : " Tliese birds ai'e so different from H. nigra that it is impossible 

 to confound them. The length of the wing presents the greatest difference : that of the Peruvian species 

 exceeds the wing of R. nigra by sixty niillim. The bill is much larger and stronger. The coloring also 

 presents several differences ; the principal consists in the complete absence of the white speculum on 

 the wing, which in the North American bird occupies the terniinal half of the secondary (piills. The 

 white demi-coUar on the neck also is wanting in our bird, being indicated only by a little paler color than 

 that of the surrounding parts. The under wing-coverts are not white, but brownish gray ; the forehead, 

 sides of the face, and front part of the throat are more or less clouded with gray. The whole tail is 

 blackish brown, the rectiices with a clear border. 



" M. Jelski has indicated on the labels that the pupil is not round, but vertical, as in the cat. Dimen- 

 sions of a male : — 



Millim'. Millim. 



Length of folded wing .... 415 Length of maxilla 105 



" the tail 136 " tarsus 35 



" the bill from the gape . 135 " mitldlo toe with claw . 30 " 

 VOL. II. — 25 



