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CHAP. XIV.] THE NEOTROPICAL REGION. 31
tropical America, only one species extending south as far as
Chili. 3. Certliidea, a peculiar genus originally classed among
the finches, but which Mr. Sclater, who has made South
American birds his special study, considers to belong to the
Ccerebidce, or sugar-birds, a family which is wholly tropical.
Two species of this genus inhabit separate islands. 4. Progne,
the American martins (Hirundinidae), is represented by a
peculiar species. 5. Geospiza, a peculiar genus of finches, of
which no less than eight species occur in the archipelago, but
not more than four in any one island. 6. Camarhynchus (6 sp.)
and 7. Cadornis (4 sp.) are two other peculiar genera of finches
some of the species of which are confined to single islands,
while others inhabit several. 8. Pyroccphalus, a genus of the
American family of tyrant-flycatchers (Tyrannidai), has one
peculiar species closely allied to T. ruhineus, which has a wide
range in South America. 9. Myiarchus, another genus of the
same family which does not range further south than western
Ecuador, has also a representative species found in several of
the islands. 10. Zenaida, an American genus of pigeons, has
a species in James Island and probably in some of the others,
closely allied to a species from the west coast of America.
It has been already stated that some of the islands possess
peculiar species of birds distinct from the allied forms in other
islands, but unfortunately our knowledge of the different islands
is so unequal and of some so imperfect, that we can form no
useful generalizations as to the distribution of birds among the
islands themselves. The largest island is the least known ; only
one bird being recorded from it, one of the mocking-thrushes
found nowhere else. Combining the observations of Mr. Darwin
with those of Dr. Habel and Prof. Sundevall, we have species
recorded as occurring in seven of the islands. Albemarle island
has but one definitely known species ; Chatham and Bindloe
islands have 11 each ; Abingdon and Charles islands 12 each;
Indefatigable island and James island have each 18 species. This
shows that birds are very fairly distributed over all the islands,
one of the smallest and most remote (Abingdon) furnishing as
many as the much larger Chatham Island, which is also the nearest