BIRDS OF NORTH AND MIDDLE AMERICA. 687 



not greater than its width at same point. Wing long and pointed, 

 the outermost primary decidedly longest and exceeding distal sec- 

 ondaries by more than half the length of wing; primaries tapering 

 terminally, pointed at tips. Tail less than lialf as long as wing 

 (except middle pair of rectrices), nearly truncate, the rectrices with 

 broadly rounded ends but with extreme tips submucronate ; middle 

 pair of rectrices elongated (sometimes greatly so), tapering to their 

 acuminate tips, their plane horizontal throughout. Tarsus as long 

 as or longer than middle toe with claw, rather slender, the acrotarsium 

 with a single row of transverse scutella, except extreme upper por- 

 tion, the planta tarsi with small, roughened or spiculate scales, the 

 sides of tarsus with larger, less prominent scales; outer toe nearly 

 as long as middle toe, the inner toe decidedly shorter; hallux very 

 short; claws moderately large, rather strongly curved and acute; 

 anterior toes fully webbed, the anterior margin of tJie webs not at 

 all incised. 



Coloration. — Adults with upper and anterior portions of head 

 dusky, the rest of head, and neck, straw yellowish; upper parts 

 plain grayish brown or brownish gray, darker on primaries and tail; 

 under parts white anteriorly, shading into brownish gray posteriorly. 

 Young more or less barred. (One species with a dusky phase, 

 immaculate in adults, barred with rusty or cinnamomeous in young.) 



Range. — Circumpolar regions, soutnward in winter as far as Persian 

 Gulf, (3ape of Good Hope, Australia, Galapagos Archipelago, southern 

 Brazil, etc. (Two species.) 



KEY TO THE SPECIES OF STERCORARIUS. 



a. Length of supra-nasal saddle decidedly greater than distance from its anterior 

 end to tip of maxillary unguis; middle pair of rectrices 164-235 mm. long; tarsi 

 black, like feet. (Circumpolar regions, southward in winter as far as Brazil, 

 Cape of Good Hope, Australia, Galapagos Archieplago, etc.) 



Stercorarius parasiticus (p. 687). 

 aa. Length of supra-nasal saddle not greater than distance from its anterior end to 

 tip of maxillary unguis; elongated middle pair of rectrices 238-368 mm. long; 

 tarsi light-colored (bluish in life), in contraft with black of feet. (Circumpolar 

 regions, southward in winter to Gibraltar, Japan, New England coast, etc., 

 casually to California, Florida, etc.) Stercorarius longicaudus (p. 694), 



STERCORARIUS PARASITICUS (Linnaeus.) 



PARASITIC JAEGER. 



Adults, li gilt-colored phase (sexes alike). — Pileum and loral region 

 grayish brown; rest of head, together with neck and under parts 

 except under tail-coverts, immaculate white, the head more or less 

 strongly tinged with straw yellow; upper parts uniform brownish 

 gray, becoming darker or dusky on primaries and tail; anal region 

 and under tail-coverts uniform brownish gray; bill light horn color, 



