ARCTIC TERN. 21 



eggs from a nest, all apparently laid by the same bird." Tlie 

 general colour of the eggs varies from stone-colour to ochreous- 

 buff or olive-buff with spots or drops of black often merging 

 into confluent blotches, the underlying spots being faint 

 purplish-grey and not very distinct. Sometimes the variation 

 in the depth of the colour of the eggs is very marked, and 

 the ground-colour is so deep a rufous-brown that the black 

 markings are scarcely perceptible. The markings are generally 

 distributed over the surface of the egg, but are sometimes con- 

 gregated in confluent blotches round the larger end. Axis, i'35-- 

 i'75 inches; diam., i-i-i*3. 



II. THE ARCTIC TERN. STERNA MACRURA. 



Sterna viacrura, Naum. Isis, 1819, p. 1847 ; B. O. U. List. 



Brit. B. p. 180(1883); Saunders, ed. Yarrell's Brit. B. 



iii. p. 553 (1884); id. Man. Brit. B. p. G^z (1889); 



Lilford, Col. Fig. Brit. B. part xxviii. (1894); Saunders, 



Cat. B. Brit. Mus. xxv. p. 62 (1896.) 

 Sterna rt/r/Zr^', Temm. ; Macgill. Brit. B. v. p. 643 (1852); 



Seebohm, Hist. Brit. B. iii. p. 284 (1885.) 

 Sterna hirundo^ Miiller (nee Lath.) ; Dresser, B. Eur. viii. 



P- 255. Pl- 579 (1872.) 



Adult Male. — Similar to S. Jluviatilis, but distinguished by 

 its entirely red bill v.'ith no dark tips, and by the much narrower 

 and less distinct dark edging along the inner aspect of the 

 white shaft of the primaries. According to Mr. Howard 

 Saunders the tarsus is shorter than in the Common Tern, and 

 does not exceed the length of the middle toe without the 

 claw ; " bill blood-red ; feet coral-red ; iris dark-brown." 

 Total length, 14-5 inches; culmen, 1-5; wings, io'8 ; tail, 7-0; 

 tarsus, o'65. 



Adult Female. — Similar to the male, but with the outer 

 feathers rather shorter. Total length, 14 inches; wing, io"5. 



Adult in Winter Plumage. — Differs from the summer plumage 

 in wanting the black cap ; the forehead and crown being 

 mottled with white, and the hinder crown and nape from the 

 eyes backwards black ; under parts whiter, with scarcely any 

 grey shade on the breast ; bill and feet duller. 



