I Have received from my friend Mr. W. F. Smeeth a paper entiled “A Perlitic Pitchstone from the Tweed River, New South Wales, with remarks on the so-called Perlitic Structure in Quartz,” published by the Royal Society of New South Wales. While thanking him for his courtesy in making me acquainted with his views, I desire at the same time to express my sense of the kindly way in which he has criticized, though often adversely, certain statements already published by me. It may be of interest to give to the readers of the GEOLOGICAL MAGAZINE an abstract of the excellent piece of work which Mr. Smeeth has done, as well as to draw attention to the points in which he has compelled me to agree with him and to remark on those on which there is still some difference of opinion between us.