NATATORES. 403 



Crown of the head, back of the neck, circle round and a 

 spot before the eye black ; forehead white ; back and wings 

 delicate silvery grey ; outer web of the external primary dark 

 grey at the base, gradually passing into light grey at the tip ; 

 all the under surface, rump, and tail pure white; irides 

 black ; bill, tongue, and feet rich orange yellow. 



Total length 10 J inches ; bill If ; wing 7^ ; tail 4 J ; tarsi -f^. 



Genus GELOCHELIDON, Brehm. 



The Gull-billed Tern of the British Islands {Gelochelidon 

 anglicd) is a typical example of this genus. The form also 

 occurs in America, and in Australia. 



Sp. 608. GELOCHELIDON MACROTARSA, Gould. 



Long-legged Tern. 

 Sterna macrotarsa, Gould in Proc. of Zool. Soc, part v. p. 26. 



Gelochelidon macrotarsa, Gould, Birds of Australia, foL, Supp., pi. 



Many years have elapsed since a small collection of Au- 

 stralian birds was sent to the Council of King's College, 

 London, as a donation to their museum. In this collection 

 was a fine species of Tern, which proved to be new to science, 

 and of which I published, in 1837, a full description, together 

 with its admeasurements, under the name of Sterna macro- 

 tarsa. In the interval between 1837 and 1865, I have only 

 seen two other examples ; it is evident, therefore, that the 

 bird is extremely rare, or that no collector has visited its true 

 habitat. One of the two specimens referred to was procured 

 by the late Mr. Elsey on the Victoria River in North-western 

 Australia, and is now in the British Museum ; the other was 

 obtained at Moreton Bay. The Gelochelidon macrotarsa is 

 considerably larger in all its admeasurements than the Gull- 

 billed Tern of Europe, to which species it is nearly allied, and 

 of which it is evidently the representative on the Australian 



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