992 SYSTEMATIC SYNOPSIS.— LONGIPENNES. 



tip rather acute; red in part in adult. Folded wings reaching beyond tail. Tail of moderate 

 length, even, slightly einarginate in young. Feet rather large. Tarsus equal to middle toe 

 and claw. General colors dark ; tail mostly blackish. Adult (J 9 , in breeding plumage : 

 Bill bright vermilion red, black on terminal third, sometimes wholly red ; a red ring around 

 eye. Head white; this color gradually merging on neck into plumbeous-ash, which extends 

 over whole under parts, being lighter on abdomen and under tail-coverts than elsewhere. Back 

 deep plumbeous-slate, lighter on rump. Upper tail-coverts clear ashy. Upper surfaces of 



wings like back ; primaries 

 black ; tips of all, except 2 

 or 3 outer ones, narrowly 

 white. Tail black, nar- 

 rowly tipped with white. 

 Legs and feet reddish-black. 

 Young-of-the-year: Smaller 

 than adult. Bill and feet 

 brownish - black. Entire 

 plumage deep sooty or fu- 



FiG. 685. — White-headed Gull, 2 nat. size. (From Sclater and Salvia.) ,. . ,i i- i „ i 



Ijginous - blackish ; all the 

 feathers, but especially those of back and upper wing-coverts, edged with grayish-white. 

 Primaries and secondaries black, as in adults, with only traces of white tips on the former. 

 Tail black, very narrowly tipped with dull white. Immature : Bill as in adult. Head all 

 round, and throat, mottled with brownish -black and dull white, the latter color predominating^ 

 on forehead and throat. Upper tail-coverts lighter than in adult, and the white tips of the tail- 

 feathers broader ; otherwise generally as in adult, but with all colors rather deeper. Length 

 17.50-20.00; wing 13.50-14.00 ; tail 5.75; bill along culmen 1.80; along gape 2.40; depth at 

 base 0.55; at angle about the same ; tarsus 2.20; middle toe and claw a little less. Young: 

 wing 12.25; tail 4.75; bill along culmen 1.00; depth at base 0.50; at angle 0.45; tarsus 1.90. 

 Pacific coast of North America, from British Columbia to Panama; common on the California 

 coast. This species is one of a dark-colored group, other members of which are modestus and 

 belcheri of the Pacific coast of South America, crassirostris of Japan and China, etc. 

 RIS'SA. (Icelandic name, rissa, ritsa, rita, or ritur; old Danish, ryttern.) Kittiwakes. 

 Three-toed Gulls. Bill stout, rather short, little compressed at base, shorter than head, 

 equal to middle toe without claw ; tip decurved and attenuated ; convexity of culmen regular 

 and gradual from base to tip; gonys concave, in consequence of great deflection of apex of 

 lower mandible ; outline of rami slightly concave ; erainentia symphysis well marked and acute, 

 but not large. Wings very long, pointed, reaching beyond tail. Tail moderately long, even 

 or (in young) emarginate. Tarsus remarkably short, less than middle toe alone ; anterior toes 

 long, and united by broad, full webs with uuincised margins. Hallux rudimentary or not well 

 developed, the ungual phalanx being generally obsolete. Pattern of primaries and livery of 

 the young peculiar. Nestlings unspotted. Nests on cliffs over the water. 



Analysis of Species and Subspecies. 



Feet dark ; bill clouded with olivaceous, about 1.50 ; wing 12.00. 



Hallux rudimentary, without a claw-bearing phalanx. Arctic and N. Atlantic tridactyla 



Hallux better formed, usually bearing a claw N. Pacific /. kotzebuei 



Feet coral red (drying yellow) ; bill clear yellow, about 1.20; wing 13.00 N.Pacific brevirostris 



R. tridac'tyla. (Gr. rpibaKTvXos, tridahtulos, tridigitate, having three digits; rpels, treis, in 

 composition rpi-, iri-, three, and daKTvXos, daktulos, a digit. Lat. ires or tris, three ; dactyluSy 

 a digit.) Common Kittiwake or Cattiwicke. Tarrock. Pick-me-up. Coddy-moddy. 



