20618. Coe, W. R.   Biology of Crepidula williamsi, a new species of prosobranch gastropod from the Pacific Coast.   Wister Institute of Anatomy and Biology, 1947, Journal Morphology, 81 (2) : 241-248, 2 figures.   Printed wraps, usual signs of use and age discoloration, text in very good condition.    $4.00