Water Birds N. Amer. ii. Boston, 1884, p. 56.
Voy. Beagle (1890 ed.), p. 244; cf. Cunningham, Voy. Nassau, 1871, pp. 91-97.
Fine alternate dusky and white lines produce a grey effect at a short distance.
A. Newton, Dict. Birds, 1896, pp. 841-842.
I can hardly agree with Count Salvadori in placing Aex here.