If any of your readers have kept Penguin Ducks, and will have the kindness to observe one little point, and communicate the result, I should be greatly obliged.² On examining the skeleton, I find that certain bones of the leg are longer than in the other breeds. I formerly kept these birds alive, and as far as I dare trust my memory, they could run considerably faster than other Ducks.³ Is this the case? It would, perhaps, be a good way to test their running powers to call the two kinds, when hungry, from a distance to their food, and see which arrived first.—

Charles Darwin, Down, Bromley, Kent.