In the ' Catalogue of Birds in the British Museum' the genus Zosterops is, placed by Gadow among the Meliphagidae, but he remarks with regard to the Zosteropinae that their degree of relationship with Meliphagidae is doubtful and that they might, perhaps, with more propriety be ranged with the Dicaeidae.
Seeing, therefore, that the position of Zosterops is still doubtful and that none of the true Meliphagidae are found in India, I am disposed for the present to place Zosters with the Sibiinae, with many genera of which subfamily it has undoubted affinities, especially with Yuhina.
In Zosterops the bill is about half the Length of the head, slender, curved and pointed, and the nostrils are covered by a large membrane. The head is not crested. The eye is surrounded by a circle of small white feathers, which gives a characteristic appearance to the bird. The tongue, according to Gadow, is protractile, bifid, each half broken up into numerous stiff horny fibres so as to form a brush.
The wing has ten primaries, but the first is very minute, so minute as frequently to evade observation. This first primary, in addition to being small, appears to grow over the second one, not under it, and this makes it the more difficult to be detected. Its shaft is, however, always visible with a small lens. The tail of Zosterops is short and quite square.
This genus is represented over a considerable portion of Africa, Southern Asia, and Australia. The White-eyes are all small birds found in flocks on trees, the leaves of which they search for insects with a constant twitter. Several of the Indian species are very closely allied to one another in coloration and size.
Key to the Species.
a. Chin and throat yellow; abdomen grey.
a1. Upper plumage golden yellow.
a2. Abdomen entirely grey…………………Z. palpebrosa, p. 214.
b2. Abdomen grey, with a yellow band down the middle…………………Z. aureiventris, p. 215.
b1. Upper plumage olive-green,
c2. Yellow on the chin and throat pure and confined to those parts…………………Z. simplex, p. 215.
d2. Yellow on the chin and throat tinged with green and extending to the breast…………………Z. ceylonensis, p. 215.
b. The whole lower plumage yellow …………………Z. siamensis, p. 210.