Written in the hand of Platt and one other, 32 folios: 'An attempt to account for the origin and the formation of the extraneous fossil commonly called the Belemnite', dedicated to George Parker, 2nd Earl of Macclesfield, who died March 1764. The date 1765 at the foot of the title-page (fo. 1) is therefore added later, perhaps on the completion of the work. The second hand begins on fo. 14. On fos 29 and 30 are seventeen carefully drawn sectional illustrations of the belemnite, no. 1 being torn away. On fo. 1 is 'Ex dono Auctoris 1774 Aetat. 86' in Platt's hand. Below this in another hand is 'Joshua Platt. Ob: 26to Decembris 1776 Aet: 88'. Inside the front cover is the mark C+ and another mark, the numbers 13300 and 319, and 'sale lot 5858'.