DENDROCYGNA VIDUATA. 751 
green; on each side of the neck a large dead green patch, surrounded 
by the black green of the head. Length, 14”; wing, 6”; tail, 2” 9’”. 
The females and young males want the green patch on the sides 
of the neck. According to Mr. Andersson the iris is ‘‘ bluish in the 
male ; the bill rich orange, inclining to livid on the edges of the 
lower mandible, the ‘nail’ of the upper mandible horn-colour; the 
legs and toes are shining black, tinged with dusky yellowish on the 
outer toes and the outer side of the legs. In the female the bill 
differs from that of the male in the upper mandible being dusky olive, 
with a greenish orange patch on the lower part of the base, and a 
small livid spot on each side of the ‘ nail.’ ” 
Fig. Daubent, Pl. Enl. 770. 
723. Denprocyena vipuata (L.). White-masked Duck. 
This curiously marked Tree-Duck (which is easily distinguished 
from all other species by its half-white face) is occasionally met with 
in Natal, to which place it doubtless wanders from the Zambesi, 
where it is common. We found it also abundant in Madagascar, in 
the swamps and rice-fields, and very easy of approach. The habit 
of perching on trees resembles that of the allied D. arcuata of 
India. 
In Natal, Mr. Ayres says, it is gregarious, frequenting the lakes 
and rivers near the coast. Mr. Barratt shot one near Potchefstroom, 
where, however, it is rare. Sir John Kirk states that it is very 
abundant in all marshy lands in the Zambesi district, large flocks 
arriving with the rains in November and December, but the 
species never entirely deserts the Zambesi region: it breeds in the 
marshes and on islands. Its favourite food is the seed of the 
Nymphea. During the night the various flocks pass to and fro, 
uttering a frequently repeated clear whistling note. The flesh is 
particularly fine; and settling in dense masses on the mud-banks, 
they can be had in great numbers from a canoe while passing 
the marshy regions, in which the large game are so difficult to 
precure. 
Mr. Andersson observes: “ This Duck, which congregates in 
immense flocks, is exceedingly common in the Lake-regions and 
on the River Okavango; in the latter locality it is seen most 
abundantly during the annual inundation, when much of the 
usually dry land which abuts upon the river is converted into 
