Mr. Layard's 'Birds of South Africa.' 263 



not appear to difFei- from European specimens of S. macrura, of 

 which it may therefore be considered a synonym. 



Sterna fluviatilis, Naum. Common Tern. 



The British Museum possesses two Terns from the Cape of 

 Good Hope which appear to belong to this species rather than 

 to its closely allied intertropical representative, Sterna senega- 

 lemis, Swains. Mr. G. 11. Gray informs me that one of these 

 specimens was sent over by Mr. Layard under the name of 

 Sterna brachypus, Swains. 



692. PoDiCEPS NiGRicoLLis (Gmcl.) ? Eared Grebe ? 



It is now pretty generally admitted that the Podiceps auritus 

 of Linnaeus is the species which has been more commonly known 

 as P. cornutus, while the P. auritus of authors is the P. nigricullis 

 of Gmelin. The only South-African example of this Grebe which 

 has come under my notice is a female in breeding-plumage, which 

 was obtained in the Transvaal by Mr. Ayres, by whom it was sent 

 to the llev. H. B. Tristram, together with its eggs. 



This bird differs from specimens of Podiceps nigricollis ob- 

 tained in various localities north of the tropics in the paler 

 colour of its car-tufts, as well as in its smaller dimensions, and 

 especially in its shorter bill. Mr. Tristram informs me that its 

 eggs are also smaller than the average size of the eggs of more 

 northern specimens, though not smaller than some exceptional 

 examples of the latter which are contained in his collection. 



The following Table will show the disparity in size between 

 the specimen sent from the Transvaal and three others from dif- 

 ferent localities with which it has been compared : — 



No. 



It will be interesting to ascertain, by a comparison of addi- 

 tional South- African specimens, whether these smaller dimensions 

 arc constant amongst them, and also whether they are common 

 to both sexes. 



