The Lenham Sandstones of Kent. 321 



(Helvetian-Tortonian) stage, which represents the middle part of that 

 epoch in such countries as Germany, Italy, France (S.), Holland, 

 Denmark, and Austria (Vienna Basin). Again, twenty-six of the 

 Lenham species occur as well in the Redonian beds of Gourbesville, 

 Normandy, which are either of Vindobonian or Messinian age, and 

 therefore Miocene. These Gourbesville deposits are of peculiar 

 interest. They were originally discovered by Yasseur, 1 and ascribed 

 to Pliocene or Red Crag times, having been more critically studied 

 since by M. G. F. Dollfus, 2 who in 1880 regarded them as of similar 

 age, although subsequently determining them as belonging to his 3 

 " Etage, Redonien ", which in explanation was stated to be neither 

 Helvetian nor Plaisancian, but equivalent in time to the Tortonian 

 stage of the Miocene, notwithstanding that he had previously 

 paralleled this new horizon with the Anversian Beds of Belgium. 4 

 The Redonian fauna was considered to be related to the Gedgravian 

 (Coralline Crag) of England. 



About twenty of the Lenham shells, including Anadara diluvii, 

 occur in the Upper and Middle Miocene of Holland, and a rather 

 smaller number of species in the same horizons of Denmark, as 

 determined by MolengraafE and Yan "Waterschoot Yan der Gracht 5 

 for Holland and by Ravn 6 for Denmark. The Pelecypod, Anadara 

 diluvii, is of frequent occurrence in the Lenham Beds, and although 

 unknown in the Diestian of Belgium, it is found in the Bolderian 

 (= Tortonian) and Anversian (= Messinian) of that country, as well 

 as in the Yindobonian of Germany, France, Austria, and Italy, and 

 in the Plaisancian deposits of Italy and France; its only British 

 occurrence from the Lenham sandstones was first recorded by Mr. Reid. 

 The Lenham fauna presents an interesting resemblance to that of the 

 Upper Miocene of North Germany (Reinbeck and Holstein), described 

 by Zimmermann 7 and Gottsche, 8 and regarded as Messinian or the 

 latest stage of the Miocene period, a formation-term introduced by 

 Mayer-Eymar, 9 to include Pontian-Sarmatian, Zanclean, and Miocene 

 of other authors. The North German Miocene deposits contain 

 twenty-five species of Mollusca which are also found in the Lenham 

 Beds, among them being Streptochetus sexcostatus, Zaria mlangulata, 

 Tellina ienedeni, Papillicardium papillosum, etc. 



Speaking further of this Miocene facies of the fauna, it may be 

 observed that Drillia obeliscus and Clavatula jouanneti are first known 

 in Burdigalian times, whereas Margaritifera plialcenacea commenced 

 its career in the Aquitanian stage, which forms the basal or oldest 



1 Bull. Soc. Geol. France, ser. Ill, vol. vii, p. 741, 1879. 



2 Bull. Soe. Geol. Normanclie, 1880. 



3 Assoc. Frangaise-Cherbourg, 1905, published 1906, pp. 358-70. 



4 Bull. Soc. Geol. France, ser. IV, vol. iii, p. 258, 1903. 



6 " Niederlande " : Handb. Kegion. Geol., vol. i, pt. iii, p. 53, 1913. 



6 " Molluskfaunaen I Jyllands Tertiaeraflejringer, etc.": Mus. Min. Geol. 

 Univ. Gopenhague : Paleontologiques, No. 7, 1907 (plates and text). 



7 " Ueber der Schichten der Tertiarformation welche bei Beinbeck durch die 

 Hamburg, etc." : Amtl. Ber. Deutsch. Nat. Aerz. Kiel (1846), 1847, pp. 232-4. 



8 Die Mollusken-Fauna des Holsteiner Gesteins " : Abhandl. Geb. Nat. Ver. 

 Hamburg, vol. x, No., 8, pp. 14, 1887. 



9 Cat. Syst. Foss. Tert. Mus. Zurich, 1867, pt. ii, p. 13. 



DECADE VI. — VOL. IV. — NO. VII. 21 



