From T. C. Brown   12 May 1875

Dear Sir

On looking over your new Edition of “Coral Reefs” which embraces not only your own discoveries respecting them, but also observations of other Corallists, I find it relates exclusively to recent and living Reefs, and does not enter upon Fossil Coral Reefs.¹ I am quite aware that most of the latter do not exist in well preserved distinct Reefs, and therefore only offer to the Geologist a disjointed collection of Corals—for description of which we have the Paleon Books of the French Corallists Edwardes & Haime, continued by D^r Duncan, which are valuable as containing descriptions of various species, but are defective in a very important part which forms the basis of your work on Coral Reefs—viz Coral History—² This therefore leaves a vacuum to be filled, in Fossil Coral Reefs, and which if you were young, might afford delightful employment and greatly help to establish the truths of all Coral History. My object in thus addressing you, is to inform you, that I discovered in the upper beds of the Great Oolite a distinct Coral Reef, and it being located near my residence, I have during the last four years, been collecting the Corals, numbering nearly 100 species and varieties, and having been the sole collector, have secured almost every kind by the aid of the Quarry Men.³ The result has astonished and delighted me, for I found the Reef contained almost every class, from Nullipora & Millipora to the ordinary species, and also Parasitic Corals.—⁴ It likewise clearly shews the cause of extinction of life, vizt By lime mud⁵ on depression of the Reef. So important did I consider the result that I thought it my duty to make it known, in order to encou⁠⟨⁠r⁠⟩⁠age Geologists located on other formations, to do as I had done—study any local Reef and preserve every specimen—more than this, I found I could not do, for I was not qualified to give scientific descriptions, or get up a popular illustrated work of my Reef. I have therefore endeavoured to enlist my friend P^r. Prestwich now located at Oxford on the Oolites, and I hope he will give Geologist by and by a History of a fossil Reef.⁶ To enable him to do this I hope this summer to shew him the Reef, and I have deposited in the Oxford Museum specimens of all found up to January last, which I mention, as you are more likely to visit Oxford than Cirencester, with the specimens I sent a catalogue illustrated by my pen, in which some profound Geologi⁠⟨⁠ca⁠⟩⁠l questions connected with Fossil Reefs are noticed.⁷ To give you an idea of a Nullipora, I have slipped into the envelope my nos. 1 & 2.⁸

1 shewing what I suppose to be an early stage of a Coral that must have been a hollow sphere, into which in life water entered, and when by degrees the coral marble filled it. No 2 being the same coral filled up. No 1 shews the Oolitic matter which must have been injected on depression.

Yours | Tho^s C Brown |

Charles Darwin Esq

PS after writing my letter I thought you would like to read my views on “Origins” & have sent it by the Book post.⁹