See the genealogical table to the article Bourbon.
In the edition of the Natiirliche Schopfungsgeschichte published in 1868 he made a great advance in his genealogical classification, since he now introduced the results of the extraordinary activity in the study of embryology which followed on the publication of the Origin of Species.
The mechanism for the statement of the genealogical relationships of the groups of the animal kingdom was thus completed.
On the one hand, the true method of arriving at a knowledge of the genealogical tree was recognized as lying chiefly in attacking the problem of the genealogical relationships of the smallest twigs of the tree, and proceeding from them to the larger branches.
Fritz Muller, by his studies on Crustacea (Fiir Darwin, 1864), showed the way in which genealogical theory may be applied to the minute study of a limited group.