90 



BIRDS OF BRITISH GUIANA. 



Fisr. 20. -To show the foriu of the taih 



55. Sterna liirundo. 



Common Tern. 



S/mia hiniiulo Linn. Syst. Xat. 10th ed. i. p. 137, 17oS (Sweden). 

 SttrnaJJuviatilis Xaum. Isis, 1819, p. 1847 (Ziebigk-Cothen, Gennany) ; 



Saunders, Cat. B. Brit. Mus. xxv. p. 54, 1S96 ; Brahomnie «t Chubb, 



B. S. Amer. i. p. 33, no. 323, 1912. 



Immat^ire. General colour aLove pale ash-grey, darker on the 

 oviter web o£ the first primary and at the tips of the primary-qnills, 

 outer webs of outer pair of tail-feathers also darker than the back, 

 and a few dark feathers on the lesser upper wino-coverts ; hinder 

 crown and nape black ; forehead, upper tail-coverts, inner webs of 

 tail-feathers, primary and secondary quills white like the chin, 

 throat, under winjr-coverts. axillaries. and under tail-coverts ; 

 breast, abdomen, and sides of the body tinged with grey. Bill 

 and feet coral-red : iris dark brown. 



Total length about 290 mm., culmen 4'2, wing 272, tnil (outer 

 feathers) 145, middle feathers ii'o, tarsus 21, middle toe and 

 claw 21. 



The specimen described above was obtained on the Lower 

 Mazaruni River in 1898; 



Adult male (^summer plumage). Crown of head and nape black ; 

 back and wings pale ash-grey ; primary-quills hoary grey ; outer 

 web of the first quill dark brown, as also the tips of the primaries, 

 inner webs broadly edged with white ; upper tail-coverts and 

 middle tail-feathers white, the lateral feathers grey on the outer 

 edges ; lores, sides of face, throat, under tail-coverts, and under 

 wing-coverts white; remainder of the under surface very pale grey. 



Total length 330 mm., culmeu 37, wing 270, tail 111, lateral 

 feathers 182, tarsus 19. 



Adult female [summer plumage). Similar to the adult male. 

 Wiu£ 280. 



