Has received English edition of Variation. First volume of German edition came three months ago. Comments on book.
Will send copy of recent lectures on human evolution [Entstehung des Menschengeschlechts (1868)]. Gegenbaur much interested in the subject.
Considers Selachius the ancestral form of the fish and hence of all higher vertebrates. Believes their swim-bladder became lung of amphibians.
Mentions cases of hybrid crosses between rabbits and hares producing fertile offspring.