EOCEJTE STKATA IN ENGLAND, liELGIUM, AND TRANCE. 91 



Turbonilla Deshayesi, J?, cif C. Sands of Cuise-la-Motte and Cal- 



caire Grossier. 



(Odostomia) hordeola, LamJc Upper Eocene, Paris Basin. 



Turritella multisulcata, Lamk Caleaire Grossier. 



Voluta elevata, Lamk Sables Inf6rieurs. 



spinosa, Linn Caleaire Grossier. 



The Heersian 



Are beds of very local occurrence, with a very small fauna, but 

 an abundant flora. I am not, however, satisfied with the reasons 

 assigned for placing them by themselves as a separate division. 

 The few Mollusca are those of the Lower Landenian and Thanet 

 Sands ; and the presence of the remarkable group of plant-remains 

 arises apparently from purely local conditions, due to the proximity 

 of land (chalk), to which also is to be attributed the exceptional 

 petrological character of the beds, which consist in great part of a 

 white chalk-like marl, with subordinate sands. 



The two Gasteropods are Lower Landenian species ; and of the 

 16 Lamellibranchs, 10 are found in the Lower Landenian beds, 6 

 in the Thanet Sands, 2 in the Woolwich and Reading Beds, and 1 

 in the Sands of Bracheux, while 2 only are new species (named but 

 not described). Of the 12 Fishes, 5 belong to Landenian genera 

 and species, 1 is a Chalk and Upper-Eocene genus, 1 Eocene and 

 Recent, 1 belongs to a family which ranges from the chalk to recent 

 times, 2 are Upper Tertiary, while the other 2 species are referred 

 to new genera. 



The 62 plants are, with one exception, all new and peculiar to the 

 locality. They are mostly dicotyledonous plants of existing genera, 

 and have been described by De Saporta and Merian. 



There is certainly nothing in these fossils to indicate a higher 

 antiquity than the Landenian. It seems to me, therefore, that 

 these Heersian beds should be grouped with the Lower Landenian, — 

 possibly, as originally proposed by Dumont, as a lower subdivision. 

 In their general aspect the Gelinden plants seem to resemble the 

 plants of the Reading Beds. 



The Thanet Sands oe Lower Landenian. 



There can be no doubt of the synchronism of these English and 

 Belgian deposits, but I would limit their range in Erance to the 

 northern edge of the Paris Basin, and exclude the Sands of Bracheux, 

 with which they have hitherto been considered synchronous *. Eor 

 this synchronism various reasons have been assigned, the chief one 

 being the immediate superposition of both on the Chalk, and their 

 position at the base of all the Tertiary strata of the Oise and adja- 

 cent district. There has also been some confusion in the fossils 

 referred to these Sands, arising from the circumstance that, owing to 

 the slight thickness of so many of the divisions of the Lower Ter- 



* In 1855 (Quart. Journ. Geol. See. vol. xi. p. 206) I stated my opinion 

 that the Sands of Bracheux were synchronous with the Woolwich Beds, but 1 had 

 not then the means, subsequently afforded by Deshayes's later investigations, of 

 obtaining the necessary palseontological information respecting the foreign 

 locahties. 



