RHYNCHOPID-E — THE SKIMMERS — RHYN< IHOPS. 193 



the same. Basal half (approximately) of the 1 > ill bright vermilion, the mandible more scarlet, 

 shading into yellowish on the tomiuin ; terminal portion black; iris dark brown ; legs and feet 

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



interrupted by a broad nuchal collar of white. Young, first plwmagt : Upper parts li;_;hi buff, each 

 feather with a central spot of black, these Bpots largest on the scapulars ; lores and suborbital 

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



coverts slate-black, tipped with white ; secondaries pun- white for nearly the whole of the exposed 

 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 feet reddish dusky. Downy young : Above, very pale grayish buff, irregularly ami sparsely 

 mottled with blackish ; below, immaculate white. 



Adult maU : Total length, about 17."" to 20.00 inches ; extent, 4s<>" ; wing, 1 1.75-15-75 ; tail, 

 5.50, its fork, about 1.20; culmen, 2.. r >r.-2>o ; gonys, 3.4"-- 1.70 ; tarsus, 1.30; middle toe, 30- 

 .85. Adult female : 15.25 to 16.75, 44.50, 13.50-1 1.25, 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 eighl adult examples from northern localities, the 

 mandible measures from 2.90 to 4.1" inches in length (measuring from the chin), while in three 

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

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

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

 measures 3.60, and is remarkably narrow. This specimen ha- 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 i- 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 i- white, only the 

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

 iously intermediate in this respect, bo that this variation i- probably due to age. 1 Audubon 

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

 the hind part ol the neck a broad band of white, mottled witli grayish black ;" the upper parte of 



1 According to M. Taczanowski, in " Proc. Zool. Soc. Loud ," 1S74, pp. 562, 563, Peruvian specimens 

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

 ers them specifically distinct. He says: "These birds are so different from /.'. nigra that it is impossible 

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

 exceeds the wing of B. nigra by sixty millim. 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 terminal half of the sec iary quills. The 



white demi-collar 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 ; tie- forehead, 

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

 blackish brown, the rectrices with a clear border. 



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

 sions of a male : — 



MUliia Jiillim. 



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



the tail 136 " tarsus 35 



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



