312 



" I was surprised to learn that all the Terns leave Ascension as soon as the young can fly ; 

 but, from the shortness of my stay, I was unable to ascertain the precise times of their arrival 

 and departure. I should, however, judge by the appearance of the young at the time of my 

 visit, that they would all be ready to start by the end of July. Whither do they go!" 



A specimen of a tolerably closely allied species, Sterna ancestheta, Scop. (Del. Faun, et Flor. 

 Ins. i. p. 92. no. 72, 1786), stated to have been obtained on the British coast, was exhibited at a 

 meeting of the Zoological Society, on the 6th February 1877, by Mr. Howard Saunders. This 

 specimen was received by Mr. E. Bidwell from a bird-stuffer in the east end of London, who says 

 that he received it in the flesh from one of the sailors employed on a light-ship at the mouth of 

 the Thames ; but the chain of evidence as to its being really a British-killed bird is scarcely suffi- 

 ciently good. As this species has not been met with elsewhere within the limits of the Western 

 Palsearctic Region, I cannot think I should be justified in including it; but in order that, in case 

 a specimen should turn up, it may be recognized, I give the differences between that species and 

 Sterna fuliginosa as follows : — Sterna ancestheta is a smaller bird, a specimen from Paternoster 

 Island, shot by Captain Conrad, measuring — culmen 1*7, wing 103, tail 8 - 3, tarsus - 8 ; the 

 back and upper parts of the body are much lighter, or blackish slate-grey in colour, and much 

 lighter than the crown ; and the webbing of the feet differs greatly ; for instead of being con- 

 tinued to the claws between the outer and middle toe, as in Sterna fuliginosa, it only descends to 

 the last joint. Mr. Howard Saunders gives (P. Z. S. 1876, p. 665) drawings of the feet of both 

 species, showing this difference very clearly. He also remarks that in the young of Sterna 

 ancestheta the underparts are light-coloured on emerging from the downy stage, whereas in 

 Sterna fuliginosa they are dark. 



The specimens figured are an adult bird from the Florida Keys and a young bird in down 

 from Ascension. 



In the preparation of the above article I have examined the following specimens : — 



E Mus. H. E. Dresser, 

 a, b, ad. Florida Keys (Dr. Heermann). 



E Mus. Howard Saunders, 

 a, ad., b,juv., c, pull. Ascension Island, December 1876. d, ad. Howland Island. 



E Mus. F. Bond. 



a, pull. Ascension. 



E Mus. II. B. Tristram, 

 a. Samoa Islands. 



