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362 GEOGRAPHICAL ZOOLOGY. [part iv.
intermediate between the Anserine birds on the one side and
the Storks and Herons on the other." The pterolysis according
to Nitzsch is " completely stork-like." '
General Bemarks on the Distribution of the Orallce, or Wading
and Runjiing Birds.
The Waders, as a rule, are birds of very wide distribution,
the four largest families EaUidse, Scolopacidae, Charadriidse and
Ardeidse, being quite cosmopolitan, as are many of the genera.
But there are also a number of small families of very
restricted distribution, and these all occur in the two most
isolated regions, the Neotropical and the Australian. The
Neotropical region is by far the richest in varied forms of
Waders, having representatives of no less than 15 out of the 19
families, while 7 are altogether peculiar to it. The Australian
region has 11 families, with 1 peculiar. The other two tropical
regions each possess 11 families, but none are peculiar. The
Palsearctic region has 10, and the Nearctic 7 families. No less
than three families—Chionididse, Thinocoridae, and Cariamidee
are confined to the Temperate regions and highlands of South
America ; while four others,—Aramidse, Psophiidae, Eurypygidae
and Palamedeidse,— are found in Tropical America only ; and
these present such an array of peculiar and interesting forms as
no other part of the globe can furnish. The Phoenicopteridse or
Flamingoes, common to the Tropical regions of Asia, Africa and
America, but abseut from Australia, is the only other feature
of general interest presented by the distribution of the Waders.
The Order contains about 610 species, which gives about 32
species to each family, a smaller average than in the Gallinse
or Accipitres, and only about one-fourth of the average number
in the Passeres. This is partly due to the unusual number
of very small families, and partly to the wide average range of
the species, which prevents that specialization of forms that
occurs in the more sedentary groups of birds.
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