WHITE-HEADED DUCK. 125 



■white, and differ from all other AfiatidcB by the shell being hard 

 and rough, and rude to the touch, as though covered with sand. 



Degland says that it occurs in Greece, but no mention of it is 

 made by Count Miihle or Dr. Linderraayer, in their ornithological 

 catalogues of that country. It is, however, not uncommon on the 

 borders of the Black Sea. Dr. Carte, on the zoology of the Crimea, 

 says, — "Two or three were seen in the harbour of Balaklava, in the 

 month of February, 1855, fishing for small fish, shrimps, etc., diving 

 with great ease, and remaining under water a considerable time. An 

 allied species is found in the salt-water lagoons of Australia and 

 Tasmania." Lord Lilford says it is common, and he believes resident 

 in the Ionian Islands, on Lake Butrinto, and on the lagoons of 

 Nicopolis. It is much more common on the opposite African coast. 

 It occurs, according to Captain Loche, in all the great lakes of 

 Algeria, and he mentions that of Halloula. Mr. Salvin says he 

 found it commonly in the lagoon of El Baheira, and he saw it at 

 Djendeli and Zana, in the Eastern Atlas, ("Ibis," vol. i, p. 364.) 

 Favier says that it occurs on its passage at Tangier. Colonel Irby 

 says it no doubt breeds near Cadiz, but he never met with it on 

 the Spanish side of the Straits. Mr. Tristram found it on the Lake 

 of Bou Guizoun, in June, 1856, and at Tuggart, in Northern Africa, 

 in December of the same year, ("Ibis," vol. ii, p. 82.) He also fell 

 in with it, and obtained the nest and eggs, at the Lake of Halloula, 

 his visits to which I have before had occasion to refer to with 

 pleasure. 



*'We found two nests of the White-headed Duck, f Erismatura 

 mersa,) among the sedge, containing the one three, the other eight 

 eggs. These are very large for the size of the bird, almost perfectly 

 elliptical in shape, and a line longer and wider than those of the 

 Velvet Scoter; of an extremely rough texture, unlike that of any 

 other Duck, more resembling the egg of the Bean Goose, but far 

 more coarsely grained, and of a dull white colour. The habits and 

 flight of the bird are more like those of a Grebe than a Duck. It 

 often saves itself by diving, and remains under water a considerable 

 time." Mr. Tristram did not meet with this Duck in Eastern Algeria. 

 Mr. Tristram does not say that the nests he found were floating. 

 Temminck says they float like the nest of a Grebe. 



The bird when swimming is submerged in the water, except its 

 head, and its stiff tail acts as an excellent rudder to steer it about. 

 Its legs are placed beyond the centre of gravity, so that it cannot 

 walk. It is, however, an expert diver, as stated by Mr. Tristram, 

 and for this its organization beautifully adapts it. 



