Copy letter from Robert William Frederick Harrison, to Vernon Herbert Blackman, [Fellow of the Royal Society], British Museum, Natural History, Cromwell Road, S.W. 'Dear Sir, In reply to your letter of the 22nd inst., I have to inform you that the return of the plate relating to the section "Pyrocystis" of the paper by Mr. Murray and yourself has been authorized. I am, Yours faithfully, Robt Harrison Asst. Sec. R. S. [Assistant Secretary, Royal Society]'. 25 July 1898