On the Dichodon cuspidatus , Owen

Abstract

In June 1847 I communicated to the Geological Society of London a description of certain teeth and portions of jaws of an extinct Artiodactyle Mammal, from the Upper Eocene sand of Hordwell, Hants, from which were deduced the dental characters of the genus Dichodon and of the species cuspidatus . The parts described were of an immature individual, retaining, probably, the deciduous molars; and having, certainly, acquired, in the upper jaw, only the first and second true molars, and in the lower jaw only the first true molar. The second true molar in that jaw was just beginning to appear above the alveolar border; the crown of the third true molar was calcified in the upper jaw, but not in the lower one,—not sufficiently, at least, to give the true form of its crown. I have since been favoured, by the experienced and indefatigable palæontologist. Dr. Wright, of Cheltenham, with the opportunity of examining and describing an instructive portion of the right ramus of the lower jaw of the Dichodon cuspidatus containing the three permanent molar teeth, in situ , and thus supplying the tooth, m 3, which was wanting to complete that part of the mature dentition of the genus. This specimen was found by Dr. Wright near Alum Point, Isle of Wight, in a bed of greenish tough tenacious clay, No. 35 of his Section, which he regards as the equivalent of the Hordwell beds from which Mr. Pytts Falconer obtained the original fossils described by me.