Fourth letter from William Crawford Williamson, on his paper 'On the organisation of the fossil plants of the coal-measures. Heterangium Tilioeoides (Will.) and Kaloxylon Hookeri' to the Secretary of the Royal Society He has re-arranged the figures so that they 'are contained in four large plates'. Wishes to receive his paper back, add photographs of the plates and re-submit it. Subject: Botany [Published in Proceedings of the Royal Society, 1887]. 15 May 1887