Plate, diagrams of figures 1-3 showing lines of direction and transverse section of tooth by Tuffen West Diagrams of figures 1-3 (final versions published as figures 3-4 from plate VI; figure 3 unpublished) showing the lines of direction and a transverse section of the echinus tooth. See PT/62/1/2 for a final version of figure 1; see PT/62/1/3 for a final version of figure 2. 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]