Note 97 — Part II. ON THE FINAL CAUSES OF TRANSFORMATION.

[Mimas Tiliæ of Butler’s revision. The author states that this genus is “easily distinguished from Laothoë by the form of the wings, the outer margin of secondaries deeply excavated below the apex, and the secondaries narrow and not denticulated.” Here again we have a clashing of the results arrived at by a study of the ontogeny of the larvæ, on the one hand, and the founding of genera on the characters of the imagines only, on the other. Of the three species discussed by Dr. Weismann, Mr. Butler, following other authors, refers Tiliæ to the genus Mimas, Populi to Laothoë, and Ocellatus to Smerinthus. It is to be hoped that when our knowledge of the developmental history of larvæ is more complete in all groups, a reconciliation between the results of the biological investigator and the pure systematist will be brought about, so that a genus may not, as at present, have such very different values when regarded from these two points of view. R.M.]