Manual of Conchology, Structural and Systematic

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The shells are excessively variable, as is usually the casein seden tary mollusks. The author has examined very large suites of specimens, including nearly every species and variety described from the waters of North and South America, both east and west, and of Japan, Polynesia and Europe. The Australian and New Zealand forms are known to me by fewer specimens, and a number of the species of those regions I have not seen.