Letter from Peter Martin Duncan, to William Allen Miller, regarding a paper 'On the genera Heterophyllia, Battersbyia, Palaecyclus, and Asterosmilia; the anatomy of their species, and their position in the classification of sclerodermic zoantharia' by Peter Martin Duncan Had sent some rough, but faithful, sketches along with the paper, which have been passed to the lithographer Williams, who has turned them into plates. Has to explain the necessity for careful figures from the specimens, not the sketches used by mistake. Subject: Geology, Palaeontology [Published in the Philosophical Transactions of the Royal Society] 30 October 1867