[Footnote 37: _Origin of Species_, p. 71.]
[Footnote 38: Yarrell's _British Birds_, fourth edition, vol. iii. p. 77.]
[Footnote 39: _Origin of Species_, p. 89.]
[Footnote 40: _Nature_, vol. xxx. p. 30.]
From Darwinism: An Exposition of the Theory of Natural Selection by Alfred Russel Wallace.
[Footnote 37: _Origin of Species_, p. 71.]
[Footnote 38: Yarrell's _British Birds_, fourth edition, vol. iii. p. 77.]
[Footnote 39: _Origin of Species_, p. 89.]
[Footnote 40: _Nature_, vol. xxx. p. 30.]