ABSTRACT
WE are much limited in our means of obtaining information as to the anatomical structure of those numerous tribes of extinct animals which are comprehended under Cuvier’s great division of Mollusks. Their soft and perishable bodies have almost wholly disappeared, and their external shells, and, in a few cases, an internal apparatus of the nature of shell, form the only evidence of the former existence of the myriads of these creatures that occupied the ancient waters.
