The Recent Mollusca of the Chatham Islands By H. J. Finlay, D.Sc. (Most of the material on which this paper is based was collected by the Otago Institute party at the Chathams in the summer of 1924.) [Read, before the Otago Institute, November 9th, 1926; received by the Editor, 7th May, 1928; issued separately, 10th August, 1928.] Plates 38-43. Collections of shells were early made from, this locality, mostly by H. L. Travers. Numerous specimens came into the hands of Captain Hutton, who, in his Catalogue of the Marine Mollusca of New Zealand, 1873, was the first to give a connected account of this molluscan fauna. He frequently refers to the Chatham Islands in the distribution of the shells lie records, and describes a number of new species which, he states occur there alone. This rather scattered list is not substantially altered in the Manual of New Zealand Mollusca of 1880, nor in Suter's standard work of the same name (1913), except that the distribution of most species had in the interim been considerably extended, with the result that in the latter work the only two species reported as from this locality alone are the European Corbula gibba (which, of course, has no right to appear in any New Zealand list), and Dentalium opacum, (the identification of which appears to be equally worthless). In contrast to this, some 30 species are noted in the present revision as endemic to the Chathams, and some of these are so characteristic and distinct that only deplorable lumping could merge them with mainland forms. Thus Hutton's statements, fifty years old though they are, have proved substantially correct—a tribute to his good work—and his views on the distribution of many of the Chatham shells were sound. Consideration of these endemic species, and of the relationships of other forms will be dealt with in the summary at the end of this account. The systematic list itself, which follows, is based as regards order of families and genera, etc., on Hedley's admirable Check-List of the Mollusca of New South Wales, 1918, with the necessary emendations noted by Iredale in the Proc. Linn. Soc. New South Wales, vol. 49, Pt. 3, pp. 179-278, 1924. As the order is thus often considerably different from that followed in Suter's Manual, a page reference is given wherever possible to Suter's description of the species dealt with. Pull references and synonymy have, however, in no case been given, as these are in general easily obtained by looking up the single (and most important) reference placed opposite the species name. As Suter's Manual embodies all records previously made, I have taken it as the standard of reference for Chatham Island shells, but I have usually mentioned his records only when the species has not occurred in the collections seen by me. These collections are from several sources, and comprise shells (a) sent to me by friends from the Chathams, (b) beach shells collected by Messrs. Young, Allan, Marwick, and Martin, members of