Author: Jefferies, R.P.S., 1970.:
Title: The subplylum Calcichordata (Jefferies 1967), primitive fossil chordates with echinoderm affinities.
Description: Bull. Brit. Mus. (Nat. Hist.), 16: pp. 243-339,[3], many photos on 10 plates, 27 figs., refs. Plain new wrappers. Fine.

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