On visit to Boston was told by N. S. Shaler how habits of rattlesnake are consistent with natural selection. Informs CD, as rattlesnake is considered by some a difficult case for his theory.

Sends two papers ["On the physical relations of the new red marl", Q. J. Geol. Soc. Lond. 27 (1871): 189–98 and "On the red rocks of England", Q. J. Geol. Soc. Lond. 27 (1871): 241–54] bearing on the continuance of generic and specific terrestrial types, in areas of Europe and elsewhere, that lasted from the Upper Silurian to the Lias.

Comments on lamellae in Prion. Offers to send specimen for CD to examine.