92 LAfilD^. 



Sterna (Svloclielidon) poliocerca, Gray, Cat. B. Trop. Is. Pacific, 



p. 58 (18.59). 

 Thalasseus bergii, Blashm, J. f. O. 1866, p. 81 (critical) ; David et 



Oustal. Ois. Chine, p. 0O3 (1877) ; De la Touche, Ibis, 1892, p. 502 



(Foochow & Swatow). 

 Sterna galericulata, Layurd, B. S. Afr. p. 371 (1867 : nee Licht.) ; 



Gurney, Ibis, 1868, p. 262 (South Africa). 

 Pelecanopus cristatus, Walden, Tr. Z. S. viii. p. 105 (1874) ; 



Tueedd. Mem. p. 203 (1881 : Celebes). 

 Sterna bergeri, E. P. Ramsay, Pr. Linn. Soc. N. S. W. 1878, p. 302 ; 



id. op. cit. 1879, p. 102 : id. Nature,\x. p. 15 (1879). 

 Sterna burgeri, E. P. Pamsay, Pr. Linn. Soc. N. S. W. 1882, p. 41 



(Solomon Is.). 



Adult male in hreeding-plumcuje. A broad band of white 

 between the base of the bill and the crown : otherwise resembles 

 the preceding in having the mantle and tail of the same colour ; but 

 is larger, and darker grej' on the upper parts : bill chrome-yellow, 

 often tinged with dull green near the bases of both mandibles ; 

 tarsi and toes black with a reddish tinge, soles mottled with yellow. 

 Total length 20 to 21 inches, culmen 2-5, wing (average) i4"2o, 

 tail 7'5, depth of fork 3-5, tarsus 1'3, middle toe with claw 1*4. 



Female. Similar, with a slightly weaker bill on the average. 



Adult in winter. Crown mottled with white, and even some 

 of the nuchal feathers have white tips for a short time ; mantle 

 rather paler ; bill greener, toes black : otherwise like the above. 



Immature. Like the above, darker on the upper wing-coverts, 

 secondaries, and primaries, as well as on the tail-feathers, which 

 are dark ash-grey, especially on the outer webs and near the tips. 



Yovnf/. Forehead and lores dull white, closelj' streaked witli 

 brownish black, crown and nape more boldly streaked with black, 

 mantle mottled with black and huffish white ; primaries chiefly 

 dark brownish grey, the shafts brown ; tail-feathers dark grey, 

 tipped with white ; iinderparts chiefly white, the neck and throat 

 streaked with brown ; bill olivaceous yellow. 



No other young Tern of the grej^-mantled group is quite so dark 

 as this. 



Nesflinff (Kottnest Island, Australia). Upper parts pale stone- 

 colour, spotted and streaked with umber-brown, underparts dull 

 white ; bill and feet ochreous. 



In this fine Sea-Tern the variation in size and in the tint of 

 the upper parts in individuals is considerable, and this has given 

 rise to the institution of several supposed species, which I cannot 

 consider valid. As regards size, the smallest are those from the 

 South of Australia, where the conditions of life are probably 

 unfavourable to full development, though even in Tasmania 

 some individuals have a wing-measurement of 14 in. In North 

 Australia birds are nearly as large as those from the Red Sea and 

 Mokran Coast, and there is every gradation over the area frequented. 

 In colour, the birds with the darkest upper parts are those 

 from the Red (" ^S'. velo.c ") and Arabian Seas and the Bay of 

 Bengal, and these dark birds — slightly falling off in size — run down 



