"The following catalogue is intended to include all the now known to inhabit the that are not included in 's edition of 's Invertebrata of Massachusetts, published in 1870. In the "New England Region" I include, on the north, the coasts of Nova Scotia and , and their outlying banks; while on the south, I include the entire region, about 100 to 120 miles wide, between the shore and the , off the southern coast of New England, and embracing all depths down to 600 s. ... I have also included the free-swimming and floating forms, ordinarily inhabiting the same region, which may be considered as meeting and including the innermost edge of the Gulf Stream in summer, but most of these surface forms are usually to be found, in summer, far inside the actual limits of the Gulf Stream. The and the northern parts of the I have considered as extra-limital, for my present purposes. Those localities are inhabited by an extremely , including many species of mollusca that have not yet been found farther south. Among these are several species of ' and allied genera."