Plate, figures 1-3 showing enamel on dorsal surface and vertical sections of keel by [Henry] Hyde Salter and Tuffen West Figures 1-3 (published as figures 6-7 from plate VIII; figure 3 unpublished) showing the enamel on the dorsal surface of an echinus tooth and vertical sections of keel. Subject: Zoology / Physiology Published in Philosophical Transactions as 'On the structure and growth of the tooth of echinus'. Received by the Royal Society on 5 March 1861. Read 21 March 1861. [1861]