The collection of Mr. Baker, at Woodbridge, contains a tooth from the Suffolk Bone-bed, indicating a Mastodon of the section Trilophodon. The tooth appears to be the upper penultimate molar of the left side. Its chief peculiarities are its great breadth, approaching M. (Trilophodon) tapir oides; the shortness of the ridges, the cingulum well marked in parts; the absence of a posterior and presence of an anterior talon. It apparently belongs to Falconer's section, “Colliculi obtusi—valliculasque transversæ.” From a number of measurements and examinations of specimens of M. angustidens in the British Museum, of M. Borsoni and tapiroides in Paris (which I have to thank M. Lartet for very kindly showing to me), and M. Borsoni at Le Puy in the Haute Loire, I consider that this tooth, comes nearest to the corresponding tooth of the huge Pliocene Mastodon Borsoni, though the cingulum and talon (very variable parts of the tooth) are unusually marked in Mr. Baker's specimen.