134 THE VOYAGE OF H.M.S. CHALLENGER. 



One specimen. Christmas Harbour, Kerguelen Island. 



One specimen. Betsy Cove, Kerguelen Island.] 



The first is nearly adult ; but the black head is not yet fully assumed, and the bill 

 and feet are still reddish-black ; in the second the black head only is wanting to complete 

 the nuptial dress ; but the third is in full breeding plumage, as is also a specimen in 

 sjairits. 



The specimen from Betsy Cove is a young bird just fledged, many particles of down 

 still adhering ; general colour sooty gi'ey mottled with brown, and barred with black on 

 the upper parts ; under- wing coverts white. 



This somewhat specialised form has hitherto been only found at Kerguelen Island, 

 and appears to be more closely albed to the New Zealand species Sterna antarctica, 

 Wagler, than to the less restricted form Sterna vittata, which also includes in its range 

 portions of the same island. The principal specific distinctions of the two species are 

 given in my paper on the Sterninse above referred to. 



[Large flocks of this Tern hovered over the beach as we first landed at Christmas 

 Harbour, were clipping down into the ripples, and picking up something, which was 

 apparently a little red copepod, the dead bodies of which formed a long line left by the 

 retiring tide.] 



3. Sterna vittata, Gm. 



Sterna vittata, Gm., Syst. Nat., vol. i. p. 609 (1788); Saunders, Proc. Zool. Soc, 1876, p. 647, 

 et 1877, p. 795. 



[One specimen. Inaccessible Island, Tristan da Cunha, 18th October 1873. 

 One specimen. Royal Sound, Kerguelen Island, January 1874.] 

 Both these specimens are adults in breeding-plumage ; but the latter is not a very old 

 bird, the outer webs of the long tail-feathers being still slightly tinted with grey, whereas 

 in really mature examples they are long and white. In pointing out its specific characters 

 (I. s. c), I gave its then known range as from Kerguelen Island up to St Paul's and 

 Amsterdam Islands, about 700 miles to the north, apparently its headcpaarters, and as 

 that of a straggler over the sea between St Helena and Ascension ; but the fact of its 

 having been obtained close to Tristan da Cunha is an interesting extension of these limits. 

 When treating of the few examples then available from the above-mentioned localities, I 

 remarked that the affinities of this species were decidedly with Sterna hirundinacea, Lesson 

 (Sterna cassini, Scl.), of the extra-tropical coasts of South America and of the Falkland 

 Islands ; and this view has subsequently been confirmed by the examination of a larger 

 series brought home by the French naturalists from the Transit-of- Venus Expedition, at the 

 same time that the two species- are always perfectly distinguishable. But in the case of 

 this individual from Tristan da Cunha (its nearest known approach to South America), it 

 is interesting to observe that, although the example is undoubtedly referable to Sterna 



