The teeth under consideration in this paper were derived from the Kargalinsk copper mines in the government of Orenburg, Russia. These mines are in the marls and sandstones overlying conformably the Zechstein or Magnesian Limestone, and were referred by Murchison to the upper division of the Permian. Other writers have regarded them as belonging to the Lower Trias, so that the question of their horizon is still sub judice. I have elsewhere explained my reasons for believing them to form part of the Permian formation, and wishing to avail myself of the latest Russian opinions, I have recently asked Dr. Trautschold, the esteemed palæontologist of Moscow, what is the state of opinion now, and he informs me that there are as yet no positive data on which to base a Triassic hypothesis. Dr. Trautschold has visited and examined the locality, an advantage not possessed by many of those who consider the series must be Triassic, because reptilian remains of a high grade are found in them.