 Later, James Sowerby and James De Carle Sowerby began to catalogue British examples in earnest.Etheldred Benett added several Upper Jurassic species, although her work was not primarily recognised due to the academic status of women at that time.In 1840 Europe, Louis Agassiz published a large volume entitled "Memoire sur les Trigonies" which recognised the large variation encountered within the family, dividing it into eight sections, which was a precursor to the generic classification that occurred some fifty years later.