General: Romanes, Darwin and After Darwin, 1892, vol. I, chaps. I-V;
Same author, The Scientific Evidences of Organic Evolution; Weismann,
Introduction to the Evolution Theory, 1904; Osborn, Alte und Neue
Probleme der Phylogenese, _Ergebnisse der Anat. u. Entwickel._, vol.
III, 1893; Ziegler, Ueber den derzeitigen Stand der Descendenzlehre
in der Zoologie, 1902; Jordan and Kellogg, Evolution and Animal Life,
1907, chaps. I and XIV. Evolutionary Series--Shells: Romanes, _loc.
cit._; Hyatt, Transformations of Planorbis at Steinheim, _Proc.
Am. Ass. Adv. Sci._, vol. 29, 1880. Horse: Lucas, The Ancestry of
the Horse, _McClure's Mag._, Oct., 1900; Huxley, Three Lectures on
Evolution, in Amer. Addresses. Embryology--Recapitulation Theory:
Marshall, Biolog. Lectures and Addresses, 1897; Vertebrate Embryology,
1892; Haeckel, Evolution of Man, 1892. Primitive Man: Osborn, Discovery
of a Supposed Primitive Race of Men in Nebraska, _Century Mag._, Jan.,
1907; Haeckel, The Last Link, 1898. Huxley, Man's Place in Nature,
collected essays, 1900; published in many forms. Romanes, Mental
Evolution in Man and Animals.