"c1. Cutting edges of bill more or less distinctly fringed or serrated, tip of bill rounded ... Anseriformes."
Yes, and our bird belongs in the order Anseriformes. By a similar procedure we find that our duck belongs in the subfamily Anatinæ (p. 185) and in the key to genera (p. 187) we find:
"a1. Bill not spatulate." "a2. Bill flattened, and spatulate ... Spatula."
As our duck has a flattened, spatulate bill we turn to the genus Spatula (p. 196) and as there is but one Philippine species in this genus we know that our bird is--
Oviparous, warm-blooded, amniotic vertebrates which have their anterior extremities transformed into wings. Metacarpus and fingers carrying feathers or quills. With an intertarsal joint. Not more than four toes of which the first is the hallux. (Gadow.)
Sternum with a keel; scapulæ and coracoids fused forming an acute or a right angle; foramen ischiadicum present; distal six or seven vertebræ fused to form the pygostyle.
a1. Hind toe connected by a web to the inner toe ... Pelecaniformes (p. 200) a2. Hind toe not connected by a web to the inner toe.
c1. Bill strong and decidedly hooked at the tip ... Procellariiformes (p. 84) c2. Bill weak, very small, gape very wide ... Caprimulgi in Coraciiformes (p. 295)
c1. Cutting edges of bill more or less distinctly fringed or serrated, tip of bill rounded ... Anseriformes (p. 184) c2. Cutting edges of bill not fringed.
d1. Rectrices rudimentary; or if evident not prominent, being short, soft, and hidden by the upper coverts.
e1. Tarsus flat; toes lobed ... Colymbiformes (p. 82) e2. Tarsus normal; toes not lobed.
f1. Hind toe wanting ... Hemipodii (p. 17) f2. Hind toe present. ... Excalfactoria and Megapodius in Galliformes (p. 9)
d2. Rectrices not rudimentary; if short not hidden by upper coverts.
e1. Anterior toes distinctly webbed and tarsus shorter than tail. ... Lariformes (p. 85) e2. Anterior toes not distinctly webbed; or, if webbed, tarsus decidedly longer than tail; or else bill extremely small with gape very broad and deeply cleft.
f1. Lower portion of thighs naked; or, if feathered, the bill lengthened and grooved along each side, the outer and middle toes separated for their entire length.
g1. Hind toe well developed and inserted on the level of the anterior toes; claws not excessively lengthened; loral or orbital region or both naked ... Ardeiformes (p. 157) g2. Hind toe if present, small and inserted above the level of the rest; or else size of bird small (less than 1 meter), loral and orbital regions fully feathered and middle claw not pectinate.