106 PROF. J. PEESTWICH OX THE COERELATION OF THE- 



grouping has been generally accepted, with, the exception that a 

 portion of the Lower Bagshots in the Isle of AVight has by some 

 been referred to the Lower Eocene. 



Since that period (1855), however, a group of fossils has been 

 discovered in the Ypresian Sands of Belgium which leaves no doubt 

 of their being of Lower Eocene age, and consequently the Lower 

 Bagshots must be placed on the same horizon. At Watten, between. 

 Calais and St. Omer, there is a small capping of these sands, with 

 Nummulitesplanulatus, overlying the London Clay (Lower Ypresian). 

 At Mons-en-Pevele, where the Sands are about 100 feet thick, N. 

 jplanulatus occurs in profusion. More recently, again, MM. Rutot 

 and Yincent have discovered in the same Sands in the neighbourhood 

 of Eenaix and Brussels as many as 65 species of shells, of which 

 about 20 occur in the London Clay and 44 in the sands of Mont- 

 Panisel and Cuise-la-Motte. Amongst the former are such common 

 London-Clay species as Nautilus centralis, Voluta elevata, Vermetus 

 hognoAensis, Pinna margaritacea, Fectunculus decussatus, Panoj>cea 

 intermedia, and Pholadomya virgida. 



The Lower Ypresian (London Clay) itself, in Belgium, is singu- 

 larly barren of fossils, Eoraminifera and a few rare Crustacea 

 (Zanthopsis hispinosus, &c.) excepted. It thins out both eastward 

 and southward. The Paniselian Beds, which overlie the Ypresian 

 Sands, and which have been grouped with them by M. Hebert, contain 

 a fauna related to the underlying series by means of Nwnmulites 

 j^lcmulatus, Pinna margaritacea, Nucula fragilis, and other fossils ; 

 while at the same time a large proportion of Calcaire-Grossier species 

 make their appearance. It is a local deposit, apparently forming, 

 with the Ypresian, the equivalent of the Sands of Cuise-la-Motte 

 (the Lits Coquilliers of d'Archiac), and thinuing out westward : there 

 is no representative of it in the London Basin. 



In the Hampshire Basin the Lower Bagshots form, at "Whitecliff 

 Bay, a well-defined mass of unfossiliferous yellow sands, about 

 100 feet thick, between the London Clay and the Bracklesham 

 Sands ; but at Alum Bay the division is obscure, and it is not possible 

 to draw any definite line there in the thick series of variegated sands 

 and clays lying between the London Clay and the Barton Beds. The 

 Bracklesham is probably represented by the Middle and Upper 

 portions of this series, and the Lower Bagshots possibly by strata 

 I^os. 7 to 19 (?) of my original section. It was in one of these beds 

 (ISTo. 17), a seam of fine foliated clay, that I discovered the plant- 

 remains afterwards described by De la Harpe and by Heer. These 

 plants, which are admirably preserved, differ materially from those 

 of Bournemouth. The leaves of one of them, Apeihopsis Laharpei^ 

 are supposed by Heer to belong to the tree which furnished the fruit 

 named Cuciimites variabilis^ so common at Sheppey. Altogether 

 48 species have been determined, which, on the whole, show a 

 greater affinity to the Lower than to the Upper Eocene. Thirty 

 of the genera are common to Alum Bay and Sheppey. A similar 

 fauna exists in the Lower Tertiary Beds of Wareham and Studland, 

 with which these beds are probably synchronous. 



