Contains correspondence relating to Waddington's research into pigmentation on shells, particularly Oliva porphyria. Also contains some photographic and illustrative material depicting the shells and the computer-simulated patterns, and a photocopy of a typescript of the article by Waddington and Cowe which was published under the title 'Computer simulation of a molluscan pigmentation pattern', in the Journal of Theoretical Biology. 25, 2, pp 219-25 (November 1969).