144 Animal Life 
AERIAL WATERFOWL. 
With three front toes webbed and wings very long. 
The Petrels and Albatrosses (Procellariide) are characterized by a hooked beak 
with its covering of horn divided into sections by grooves and the nostrils tubular, 
the tubes being contiguous in the Petrels and separate in the Albatrosses. The 
hind-toe is only represented by the claw, and even this may be absent. (Mig. 6.) 
N.B.—The Diving Petrels (Pelecanoides) in form and habits resemble Auks, having 
short wings and diving constantly, but the beak at once distinguishes them. 
The Gulls and Terns (Laride) possess bills with the covering of horn in one piece 
and the nostrils open and slit-like. The bill is more or less hooked in the Gulls and 
straight in the Terns. There is usually a small hind-toe, and in the Kittiwakes (Rissa), 
where it is rudimentary, the bill will distinguish the bird from any petrel. (Fig. 7.) 
The Gannets (Swltd@) exhibit straight bills with the covering divided, and no 
perceptible nostrils; the hind-toe is united to the front ones by a web, as in the 
Cormorants. 
The Tropic-Birds (Phdethontide) show also straight bills but with uniform covering and 
slit-like nostrils; the hind-toe is united to the front ones by a web, this distinguishing 
them from the Terns, which they much resemble. 
The Frigate-Birds (Fregatide) have long hooked bills with the covering in sections; 
all the four toes are united by very small webs and the legs are feathered; the 
wings are enormous, and the tail excessively long and forked. 
LONG-LEGGED WADING BIRDS. 
With well-developed hind-toe, perching much in trees, &c. 
The Herons (Ardeide) are easily distinguished by their long straight bill with the 
mouth reaching to the middle of the eye and the nostrils at the end of a groove; 
the feet have three toes in front, with short webs at the base of the outer two 
only; the hind-toe is of large size. (Fig. 8.) 
In the Storks (Ciconiide) the bill is also long, straight or curved at the end, but 
without a groove; the mouth reaches about to the eye; in the feet all the front toes 
are united by short webs, and the hind-toe is not so large as in Herons. 
The Ibises and Spoonbills (Plataleid@) have the bill long and curved downwards 
throughout or broadened and curved down only at the end (Spoonbills); the three 
front toes are united at the base by short webs and the hind-toe is well-developed, 
whereas in the Curlews, often confused with them, it is short and useless. 
N.B.—The Tantalus Storks have the bill curved down, but only at the tip, and 
this is not broadened as in the Spoonbills. 
The Hammerkop (Scopus wmbretta) forms a family by itself; it is a bird with 
comparatively short neck and legs, three toes before, all webbed at the base, and a 
well-developed hind-toe; the head crested and with a deep bill hooked at the tip, and 
the general plumage brown and buzzard-like. 
The Sun-Bitterns (Hurypygide) ave birds showing long slender bills and necks, broad 
rounded wings and large, broad tails very beautifully coloured, and feet with small but 
useful hind-toe. The short hind-toe is a sufficient distinction from the true Bitterns, 
as well as the close-feathered neck, the Bitterns proper having a full ruff there. 
USUALLY LONG-LEGGED RUNNERS OR WADERS. 
With hind-toe never large, and seldom perching. 
The Cranes (Gruide@) much resemble Herons and Storks, with which they are often 
confounded, being tall, leggy, straight-billed birds with large wings. Their feet will at 
