MolluscaBase name details
original description
Call, R. E. & Pilsbry, H. A. (1886). On <i>Pyrgulopsis</i>, a new genus of rissoid mollusk, with descriptions of two new forms. <em>Proceedings of the Davenport Academy of Natural Sciences.</em> 5: 9-14, pl. 2., available online at https://www.biodiversitylibrary.org/page/14051068
page(s): 13, pl. 2 figs 14-16 [details]
additional source
Walker, B. (1906). New and little known species of Amnicolidae. <em>The Nautilus.</em> 19(9): 97-100, pl. 5, figs. 1-7; 19(10): 114-117, pl. 5, figs. 8-18., available online at https://www.biodiversitylibrary.org/page/27052120#page/119/
page(s): 116, pl. 5, fig. 15 [details]