"Adult male and female.--General plumage brownish gray, almost uniform, without any dark markings in the center of the feathers; upper part of head and upper part of nape blackish brown; superciliary stripe, sides of head, throat, and sides of upper part of neck rufous; a blackish brown band runs across the eyes from lores to occiput; back dark gray, changing into brown on rump and upper tail-coverts; wing-speculum glossy green, bounded anteriorly by a velvety black band at the tip of greater wing-coverts and by a narrower white one at the tip of the last row of median upper wing-coverts; posteriorly the speculum is bounded by a velvety black, subapical band, and by a narrow, apical, white band; under wing-coverts and axillars white; under parts brownish gray, deepening into brown on under tail-coverts; tail brown; colors of the bill and feet not recorded, but apparently dark olive. Length, about 500; wing, 250; tail, 114; culmen, 51; tarsus, 43. "Young.--Similar to the adults, only much paler on the head and throat, which are scarcely tinged with rufous; the speculum less bright, and with some purple reflections." (Salvadori.) Iris brown; bill dark blackish blue, its nail black; legs and claws dark brown. A male from Luzon measures: Length, 635; wing, 262; tail, 114; exposed culmen, 51; bill from nostril, 40; tarsus, 43; middle toe with claw, 63. The Philippine mallard does not often occur in large numbers; usually, however, it may be found in pairs in tide creeks, small ponds, or other suitable localities. "We found this fine mallard to be rare in all the localities visited by us with the single exception of the region about the town of Milagros, on the west coast of the Island of Masbate. In the last-mentioned district it was very abundant, occurring in great flocks." (Bourns and Worcester MS.) "Extraordinarily abundant on the Abulug River in northern Luzon in March, 1906. Flocks of twenty-five to two hundred were constantly met with on the lower river." (Worcester.) Genus POLIONETTA Oates, 1899. A wide yellow band across the tip of bill, otherwise like Anas from which it is scarcely separable. 158. POLIONETTA ZONORHYNCHA (Swinhoe). ZONE-BILLED DUCK. Anas zonorhyncha Swinhoe, Ibis (1866), 394; Salvadori, Cat. Birds Brit. Mus. (1895), 27, 211. Polionetta zonorhyncha Sharpe, Hand-List (1899), 1, 217; McGregor and Worcester, Hand-List (1906), 37. Calayan (McGregor). Eastern Siberia, Mongolia, China, Japan, Kurile Islands.