Ecuador.
38. Myiarchus magnirostris Allied to West Indian species.

COLUMBIDAE.

39. Zenaida galapagensis { A peculiar species of a S.
{ American genus.

FALCONIDAE.

40. Buteo galapagensis A buzzard of peculiar coloration.

STRIGIDAE.

41. Asio galapagensis } Hardly distinct from the widespread
} _A. brachyotus._

42. Strix punctatissima Allied to _S. flammea_ but quite
distinct.

We have here every gradation of difference from perfect identity with the
continental species to genera so distinct that it is difficult to determine
with what forms they are most nearly allied; and it is interesting to note
that this diversity bears a distinct relation to the probabilities of, and
facilities for, migration to the islands. The excessively abundant
rice-bird, which breeds in Canada and swarms over the whole United States,
migrating to the West Indies and South America, visiting the distant
Bermudas almost every year, and extending its range as far as Paraguay, is
the only species of land-bird which remains completely unchanged in the
Galapagos; and we may therefore conclude that some stragglers of the
migrating host reach the islands sufficiently often to keep up the purity
of the breed. Next, we have the almost cosmopolite short-eared owl (_Asio
brachyotus_), which ranges from China to Ireland, and from Greenland to the
Straits of Magellan, and of this the Galapagos bird is probably only one of
the numerous varieties. The little wood warbler (_Dendroeca aureola_) is
closely allied to a species which {283} ranges over the whole of North
America and as far south as New Grenada. It has also been occasionally met
with in Bermuda, an indication that it has considerable powers of flight
and endurance. The more distinct _species_--as the tyrant fly-catchers
(Pyrocephalus and Myiarchus), the ground-dove (Zenaida), and the buzzard
(Buteo), are all allied to non-migratory species peculiar to tropical
America, and of a more restricted range; while the distinct _genera_ are
allied to South American groups of thrushes, finches, and sugar-birds which
have usually restricted ranges, and whose habits are such as not to render
them likely to be carried out to sea. The remote ancestral forms of these
birds which, owing to some exceptional causes, reached the Galapag