BANGS: BIRDS FROM THE LIU KIU ISLANDS. 25-1 
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. 
Measurements1— 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, 
1860); since then two specimens have been noted by Stejneger, both from the 
Yayeyama Islands, the first in Proc. U. S. Nat. 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 smal]l dark northern form of Bergius’s tern the trinomial 
given above. When Saunders wrote his account of Bergius’s tern, he hada 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 bergiit may be indicated as follows : — 
1. Sterna bergit bergit Licht., South Africa, large, gray of upper parts pale. 
2. S. bergit velox (Cretzschm), Red and Arabian Seas and Bay of Bengal, 
large, gray of upper parts very dark. 
3. S. bergit pelecanoides (King), northern parts of Australia, intermediate 
between the last two in size and coloration. 
4. 8S. bergit poliocerea? (Gould), Tasmania and South Australia, small, gray of 
upper parts pale. 
5. 8S. bergi 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 8. rectirostris 
Peale, described from the Fiji Islands. 
1 Three specimens of S. bergii poliocerca in the Mus. Comp. Zool. afford the 
following measurements : — 
No. Sex. Locality. Wing. Tail. Tarsus. Culmen. 
8,781 g Australia. 334 158 81 59.5 
12,018 g (2) Melbourne, Aust. 332 173 27 56. 
8,782 3 (2) Australia. 340 146 30 59. 
For further measurements, see Stejneger, Proc. U.S. Nat. Mus., 1887, Vol. X. 
pp. 393-394. 
