Was as authored by Walker & Jacob, but the author is Adams (1798). See the detailed explanation for Serpula bicornis Adams. Original publication (Boys & Walker 1784) is rejected for nomenclature.
Boys, W.; Walker, G. (1784). Testacea minuta rariora, nuperrime detecta in arena littoris Sandvicensis / A collection of the minute and rare shells, lately discovered in the sand of the sea shore near Sandwich / by William Boys ... ; considerably augmented, and all their figures accurately drawn, as magnified with the microscopy, by Geo. Walker, bookseller, at Faversham. [Booklet]. 25 pp, published by George Walker.