234 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Charles Lyell at p. 331 may prove to belong to a bed of that age. In 

 it eighteen named species are enumerated, fourteen of which certainly 

 occur in the Calcaire grossier, but they are met with also in the Lits 

 Coquilliers. One is peculiar to Belgium. Of the three remaining, the 

 Terebellum convolutum occurs, it is true, in the Calcaire grossier, and 

 not in the " Lits Coquilliers," but against that we have the Panopcea 

 intermedia, which occurs only in the latter, and the Vermicularia 

 Bognoriensisly a London Clay species. The Nummulites planulatus 

 does not, as before mentioned, occur here, but near Lille it abounds 

 in these beds. In Belgium, this fossil is found in strata, of which 

 the position beneath the zone of Nummulites IcBvigatus and at the 

 top of the Sables Ypresiens is well determined. Sir Charles enume- 

 rates (p. 357 and 358) sixteen other named fossils, associated with 

 the N. planulatus in the vicinity of Brussels. Of these, twelve occur 

 in both series in the Paris basin, one is peculiar to Belgium, the Tur- 

 binoUa sulcata is a Calcaire grossier species, and a Cytherea (C. oh- 

 liqua X) and a Natica {N. Hantoniensis ?) are found, which appertain 

 as much or more to beds lower than the " Lits Coquilliers*." I pre- 

 sume also, from the observations of M. d'Archiac, that the general 

 facies of the fauna must be essentially like that of the Lits Coquilliers ; 

 still it is clear that the leading evidence is the Nummulites planulatus , 

 a Foraminifer which in the " Lits Coquilliers " generally, and in the 

 Ypresian Sands occasionally, occurs in wonderful profusion, and yet 

 appears in this part of Europe to have but this limited vertical range. 



These lower Cassel sands may possibly admit, to a certain extent, 

 of a subdivision into three parts; the upper one (Systeme Paniselien of 

 Dumont) may correspond with the glauconiferous clays overlying the 

 Lits Coquilliers in the Aisne ; to this succeeds the fossiliferous band 

 more exactly synchronous with the Lits Coquilliers, as distinguished 

 by M. d'Archiac ; and then the thick mass of unfossiiiferous siliceous 

 sands corresponding with the Sables divers. Or they might be all 

 included in one division — that of the Glauconie moyenne of M. Graves. 



There are two facts apparent in the Cassel and Belgian series, which 

 are the poverty of the fauna compared with that of the synchronous 

 deposits in the Paris basin, and the more purely siliceous condition 

 of the strata. 



If now we pass to the London Tertiary district, and take the first 

 range of hills where the beds above the London Clay are well deve- 

 loped, viz. the Bagshot Hills, we shall find that they present some 

 remarkable stratigraphical resemblances with the hill of Cassel. The 

 Lower Bagshot sands are about 130 feet thick, and consist of light- 

 coloured siliceous sands, with a few thin subordinate argillaceous 

 beds, and a very few concretionary blocks of hard siliceous sandstone. 

 In position and general basic structure they agree very closely both 

 with the Cassel beds and the "Glauconie moyenne" of M. Graves 

 (Et. 1, 2, and 3 of M. d'Archiac). The main difference consists in the 

 absence of intermixed green sands, of calcareous matter, and of solidi- 

 fied beds ; all these, however, are subordinate features subject to great 

 variation, even in the Paris district. The only superadded feature in 

 * The " Cancer Leachii " (?) is also quoted. 



