All three of the G.B Sowerbys published extensively on the subject of conchology, which is the collection and study of shells. Even for professional taxonomists it is difficult to know which of the three "G.B. Sowerbys" is meant in a particular citation. The numbering system G.B. Sowerby I, II, or III helps. "Sowerby, 1870" can refer to either G.B. Sowerby II or G.B. Sowerby III.