important in its several bearings. How sincerely I wish that you may live to discover some of the bones belonging to these gigantic birds: how eminently interesting it would be to know, whether their structure branches off toward the Amphibia, as I am led to imagine that you have sometimes suspected. The finding [of] the bones of the Rhynchosaurus in the [illegible] [illegible] sandstone of Grinshill in Shropshire (where there are some Reptile foot-steps) may give one hopes. I am preparing a little volume on the geology of S. America, which, when published next September. I will beg you to do me the kindness to accept; though it is a miserable acknowledgment for your great work. With my sincere thanks and much respect, please believe me, dear Sir, yours faithfully and obliged,
C. Darwin