Evolution

Essays on Darwinism

At the Deathbed of Darwinism: A Series of Papers

Biology

On the Tendency of Species to Form Varieties

Evolution: An Investigation and a Critique

Pleistocene Pocket Gophers From San Josecito Cave, Nuevo Leon, Mexico

The Social Direction of Evolution: An Outline of the Science of Eugenics

Man's Place in the Universe A Study of the Results of Scientific Research in Relation to the Unity or Plurality of Worlds, 3rd Edition