RHYNCHOPID.E — THE SKIMMERS — RIIYNCHOPS. 19''3 



the same. Basal half (approximately) of the liill Inight vermilion, the mandible more scarlet, 

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

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

 interrupted by a broad nuchal collar of white. Young, first j)luma(je : Upper parts light buff, each 

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

 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 Avhite at the ends. Lower parts entirely pure wliite. 

 Bill and feet 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; middle 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 lengtli (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 Cunchitas, 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 w^holly 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 Ijirds ?) the tail is white, only the 

 intermediaj 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 



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

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

 ers them specitically distinct. He says : " These birds are so ditlereiit 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 E. nigra by sixty millim. The bill is much larger and stronger. The coloring also 

 presents several differences ; the principal consi.sts in the complete absence of the wliite speculum on 

 the wing, which in the North American bird occupies the terminal half of the secondary (piills. 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 ; the forehead, 

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

 blackish brown, the rectrices 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. M'"™- 



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 " 

 VOL. II. — 25 



