BANGS: BIRDS FROM THE LIU KIU ISLANDS. 2b i 



white ; 2nd primary similar but black tip deeper in color and extending a short 

 distance down outer margin of inner web, thus enclosing the white of inner 

 web for a short distance ; 3rd, 4th, and 5th primaries like 2nd, but black tip 

 gradually growing deeper in color ; outer rectrices above pale smoke gray at 

 tips and along shafts, pale grayish white toward base ; 2nd and 3rd rectrices 

 darker on the outer webs and at tip and whitish toward base of inner webs ; 

 bill, in dried specimen, dull yellow clouded with olive toward base; feet and 

 tarsi blackish. 



Measurements.^ — Adult $, type, wing 344; tail 178; tarsus 28; 

 culmen 62. 



Remarks. — Sterna bergii was first recorded from this region ("breeding on 

 small islands off the north coast of Formosa) by Swinhoe (Ibis, Vol. II. p. 68, 

 1860J; since then two specimens have been noted by Stejneger, both from the 

 Yayeyama Islands, the first in Proc. U. S. Kat. Mus., 1887, Vol. X. p. 392 ; 

 the second in Vol. XIV. p. 490, 1891 . But the question Stejneger raised in 1887, 

 " Will anybody kindly inform me what name properly belongs to the smaller 

 dark birds from the China seas ? " has hitherto remained unanswered. My type 

 of Sterna bergii boreotis agrees with the descriptions of Stejneger's specimens, 

 and I propose for the small dark northern form of Bergius's tern the trinomial 

 given above. When Saunders wrote his account of Bergius's tern, he had a large 

 series of specimens at his command. He devotes but a few lines to the 

 exceedingly interesting geographical variations of this wide-spread species, and 

 after pointing out, in rather a vague way, how well marked the various races 

 are, ends by including them all under one name. 



The principal races of Sterna bergii may be indicated as follows : — 



1. Sterna bergii bergii Licht., South Africa, large, gray of upper parts pale. 



2. S. bergii vehx (Cretzschm), Red and Arabian Seas and Bay of Bengal, 

 large, gray of upper parts very dark. 



3. S. bergii pelecanoides (King), northern parts of Australia, intermediate 

 between the last two in size and coloration. 



4. S. bergii poliocerca ^ (Gould), Tasmania and South Australia, small, gray of 

 upper parts pale. 



5. S. bergii boreotis, subsp. nov., Liu Kiu Islands and Northern China 

 Sea, small, gray of upper parts very dark. 



Still another race that may prove distinct is the Polynesian S. rectirostris 

 Peale, described from the Fiji Islands. 



1 Tliree specimens of S. bergii poliocerca in the Mus. Corap. Zoijl. afford the 

 following measurements: — 



No. Sex. Locality. Wing. Tail. Tarsus. Culmen. 



8.781 d- Australia. 334 158 31 59.5 

 12,018 9 (?) Melbourne, Aust. 332 173 27 56. 



8.782 cfC?) Australia. 340 146 30 59. 



For further measurements, see Stejneger, Proc. U. S. Nat. Mus., 1887, Vol. X. 

 pp. 393-394. 



