Letter | Published:

Optical Projection as an Aid in Studying Plane Spiral Coiling of Small Fossil Lamellibranchs

Nature volume 150, pages 5758 (11 July 1942) | Download Citation



THE use of optical projection in certain screw-gauges1 and pivot-wear meters2 suggested methods for examining the kind and degree of variation shown by plane spiral coiling in a group of small and well-preserved lamellibranchs (Gryphœa incurva (Sow.)) when researches upon these variations were extended3 in this Department recently. Identical methods proved applicable to the study of small ammonites and other shells, whether fossil or recent, provided they were coiled in a plane spiral.

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  1. Geology Department, University of Glasgow. June 27.

    • A. T. J. DOLLAR


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