A HISTORY OF KENT eagle-ray, Myliobatis goniopleurus and M. toliapicus, described on the evidence of their roller-like dental plates from Sheppey. An extinct species, Rhinoptera daviesi, of an allied living genus, is known by a single specimen of the dentition in the British Museum. The long-tailed eagle-rays, whose dentition differs from that of Myliobatis by having no lateral plates, are represented in this formation by Aetobatis irregularis, a species described on the evidence of Sheppey specimens but also occurring in other Eocene deposits. Among the sharks, the existing genus Notidatius, characterized by its comb-like teeth, is represented at Sheppey by N. serratissimus, a species somewhat widely spread in the Eocene, but typically from that locality. Of sharks allied to the existing porbeagle the widely spread Lamna macrota, Otodus obliquus, Odontaspis elegans, and O. cuspidata have left their sharply pointed teeth in the clay of the Isle of Sheppey, but neither species is typically Kentish ; the species of Odontaspis also occur at Heme Bay. A small relative {Carcharodon subserratus) of the great Rondeleti's shark of modern seas is typified by a single tooth from Sheppey in the collection of the British Museum. Of fishes allied to the existing chimera, or king of the herrings, dental plates referable to two extinct genera are not uncommon at Sheppey. One of the species, Edaphodon bucklandi, was first described from the Middle Eocene of Sussex, but the second, Elasmodus hunteri, although also common to the Middle Eocene, is typified by a Sheppey specimen in the Museum of the Royal College of Surgeons. Very interesting is the occurrence in the London Clay of Sheppey of dermal bones of a sturgeon, which have been provisionally assigned to the typical living genus under the name of Acipenser toliapicus they afford the earliest known evidence of true sturgeons. Of the pycnodont ganoids — those hard-scaled extinct fishes with a pavement of bean-like crushing teeth in the mouth — the species Pycnodus toliapicus and P. bowerbanki are both peculiar to Sheppey, the latter being apparently only known by the type specimen in the British Museum. To a more modern type of fish — the Elopidce, relatives of the herrings — belongs a fossil in the British Museum from Sheppey which is provisionally assigned to the living genus Elops. Two extinct species, Megalops priscus and M. oblongus, of the other existing genus of the family, are peculiar to the Sheppey deposits ; the same being the case with Esocelops cavifrons, the sole representative of its genus, and known only by a couple of specimens in the national collection. In the alUed family Albulidce, the typical genus, of which one tropical species still survives, is represented by Albula oweni in the Sheppey deposits, a species apparently also occurring in the Middle Eocene of Belgium. The genus and species Brychcetus muelleri, belonging to the family Osteoglossida, now characteristic of the southern hemisphere, have been described recently by Dr. Smith Woodward on the evidence of remains from Sheppey in the British Museum. In the herring family {Clupeidce) re- 36
