Thanks AD for his Ursprung [der Wirbelthiere (1875)], which astonished CD. AD’s views, if accepted by competent authorities, will show how much we have to learn about the history of every animal. Suggests caution on "degradation principle". Comments on other views in the work. Has long seen importance of the principle of "Functionswechsel" [transfer [change!?] of function], but never enunciated it as a distinct principle.

Reports some details of the geological tour he took with Sedgwick in North Wales in 1831. Recalls how neither he nor Sedgwick saw the obvious signs of past glaciation.