Through the generosity of Mr. W. Hill, the Museum of Practical Geology possesses a tooth found in the “Totternhoe Stone” in the -neighbourhood of Hitchin, which is of especial interest inasmuch as it is undoubtedly closely related to Iguanodon, and is of later date than any British Dinosaurian remains hitherto recorded; the Acanthopholis horridus of Prof. Huxley, from the Chalk Marl, and the Trachodon (Hadrosaurus) Cantabrigensis, of Mr. Lydekker, from the “Cambridge Greensand,” being, up to the present time, the most recent of known British Dinosaurs. Remains of allied forms, however, have been found at a higher horizon of the Chalk of Maestricht, and have been described by Prof. Seeley, and M. L. Dollo.'