From:
Samuel Pickworth Woodward
To:
Charles Robert Darwin
Date:
2 May 1856
Source of text:
DAR 181: 153
Summary:
Proportion of molluscan species to genera in various periods. The difficulty of determining species increases with the number of species per genus. Identifying species within a genus is most difficult in that period in which the genus shows its greatest development.
Contributor:
Darwin Correspondence Project