_Plotus anhinga_, the Snake-bird or Darter of tropical and sub-tropical America, ranging northwards to West Mexico and South Carolina, is glossy greenish-black with beautiful silvery-grey markings on the scapulars and wing-coverts, a broad brown tip to the tail, which becomes white terminally, and long whitish hair-like feathers on the sides of the occiput and neck, merging into a black mane on the nape. The filoplumes are absent in winter, and are inconspicuous in the female, which differs, moreover, in having a grey-buff head, neck, and breast, the latter being divided from the belly by a chestnut band. The young resemble the mother-bird, but are duller and lack the chestnut tint. The peculiar long thin neck and corrugated rectrices have been mentioned above; the plumage is unusually close, and is chiefly composed of small soft feathers of very uniform distribution; the lores, orbits, chin, and throat are naked, the two former being apparently greenish, and the latter, which is moderately dilatable, orange. The bill is olive above and yellow below, the feet mainly olive with yellow webs. Three other species are recognised, but the variability in the amount of rufous in all makes their validity somewhat questionable. They are _P. novae hollandiae_ of Australia, New Zealand, and New Guinea, with a {80}white stripe on the sides of the head and a white border to the gular sac; the almost identical _P. melanogaster_ of the Indian Region, extending to Celebes; and _P. levaillanti_ of the Ethiopian Region–described also from Antioch as _P. chantrii_–which has a rufous crown, buff throat, and chestnut greater wing-coverts. [Illustration: FIG. 23.–Indian Darter. _Plotus melanogaster._ × ⅕. (From _Nature_.)]