434 STERNID.E STERNA 



B. Tail longer, at least half the length of the wing. 



a. Of large size, wing over 14*0 ; forehead white 



(in breeding dress) ; a crest of elongate 



feathers on the nape S. bergii, p. 436. 



b. Of intermediate size, wing between 8 and 13 



inches. 

 a 1 . A nape crest ; legs black, mantle grey. 



a 2 . Bill black, yellowish at the tip S. cantiaca, p. 437. 



b 3 . Bill yellow 8. media, p. 438. 



ft 1 . No nape crest, legs red to livid, mantle 



grey. 

 ft 2 . Inner web of primaries edged with white 



to the tips of the feathers S. dougalli, p. 439. 



b 3 . Inner web of primaries edged with white, 



not extending to the tip of the feathers. 

 a 3 . Outer web of streamers very slightly 



grey S. vittata, p. 439. 



6 3 . Outer web of streamers distinctly grey. 



a 4 . Dark band on the inner web along 



the shaft of the primaries broader, 



occupying about half the web S.fluviatilis, p. 440. 



fe 4 . Dark band on the inner web along 

 the shaft of the primaries narrower, 

 occupying only about a quarter the 



width of the web S. macrura, p. 442. 



c 1 . No nape crest, legs blackish, mantle sooty 



black S. fuliginosa, p. 444. 



c. Of small size ; wing less than 8'0. 



ft 1 . Forehead black to the base of the bill ; bill 



black S. balcenarum, p. 442. 



fe 1 . Forehead white. 



a 2 . Only the two outer primaries darker than 



the inner ones S. minuta, p. 443. 



b 2 . The three outer primaries darker and con- 

 trasting with the inner one S. saundersi, p. 444. 



Jfactwfri-frfnA 



^ o * 



759. Sterna caspia. Caspian Tern. 



Sterna caspia, Pall., Nov. Comm. Petrop. xiv, i. p. 582, pi. 22, fig. 2 

 (1770) ; Kirk, Ibis, 1864, p. 337 ; Layard, B. S. Afr. p. 369 (1867) ; 

 Finsch Sf Hartlaub, Vog. Ost-Afr. p. 826 (1870) ; Gurney, in Ander- 

 sson's B. Damaral. p. 359 (1872) ; Dresser, B. Eur. viii, p. 289, pi. 

 584 (1877); Sliarpe, ed. Layard's B. S. Afr. p. 703 (1884); FlecJc, 

 Journ. Ornith. 1894, p. 379; Shelley, B. Afr. i. p. 163 (1896); 

 Reichenoiv, Vog. Afr. i. p. 56 (1900). 



Hydroprogne caspia, Saunders, Cat. B. M. xxv, p. 32 (1896). 



