Description of the Rodent Teeth of Mimomys from Castle Eden

Abstract

These specimens are an incisor and an anterior cheek-tooth ( m. 1 of ordinary numeration), both of the left upper jaw; they probably come from one animal, and are accompanied by some minute fragments of the premaxillae and maxillæ. The cheek-tooth is obviously young, since its worn surface shows thin enamel and confluent dentinal spaces; an examination of the pulp-cavities shows that the dentinal spaces would be closed by the re-entrant enamel folds in more adult stages of wear. In size both teeth agree perfectly with those of the species of Mimomys which occur in the Upper Freshwater Bed of West Kunton (Norfolk). Further, the crown pattern of the cheek-tooth shows certain minute features, of an ephemeral kind, similar to those that I have observed in correspondingly young teeth of Mimomys , The tooth shows no sign of rooting, and rooted molars are, of course, the most striking characteristic of Mimomys — when adult; but similarly young teeth of Mimomys from West Kunton are wholly without signs of rooting also. The Durham material is insufficient for me to say positively that it should be referred to Mimomys ; but had I found it at West Runton or in the High-Terrace Drift of the Thames I should have had no hesitation in determining it as the remains of a young individual of that genus. It is to be hoped that further search will be made in County Durham; for these specimens lead me to believe that somebody has a very good chance of making an