To O. C. Marsh   31 August 1880

My dear Prof. Marsh

I received some time ago your very kind note of July 28^th, and yesterday the magnificent volume. I have looked with renewed admiration at the plates, and will soon read the text.¹ Your work on these old birds, & on the many fossil animals of N. America has afforded the best support to the theory of evolution, which has appeared within the last 20 years. The general appearance of the copy which you have sent me is worthy of its contents, and I can say nothing stronger than this.

With cordial thanks, believe me yours very sincerely | Charles Darwin