24*0 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 25, 



Nuculasimilis,-S'(w^;.(N.margaritacea,Zam.) Teredina antenautse, Sow. (T. perso- 



Ostrea flabellula, Lam. nata, Lam.) 



Panopaea intermedia, Sow. (? P. remensis, Turritella edita and T. conoidea, Sow. 



Mel., Corbula dubia, Desk.) (T. imbricataria, var. Lam.) 



Cardium semistriatum, Desk. Venericai'dia planicostata, var. Lam. 



Pholadomya margaritacea, Sow, (? V. Suessoneusis, d'Areh.)* 



Pectunculus pulvinatus, Lam. Pleurotoma undata, Lam. 



Pinna affinis, Sow. (P. margaritacea, Lam.) Natica labellata, Lam. 

 Pyrula tricostata. Lam. 



In Belgium also, M. Galeottif mentions the Pholadomya marga- 

 ritacea, a Pectunculus, (apparently P. brevirostris) Cassidaria caru 

 nata, a Calyptrcea and a Teredina, as occurring amongst the fossils 

 of his lowest group (systeme inferieure). 



Combined with the other characters, this list affords strong pre- 

 sumptive evidence that the ' Lits coquilliers ' and the Bognor beds 

 are members of the same group, and nearly synchronous. The 

 number of species common to the two is considerable, and gives a 

 per centage equal to, or greater than, that of the species common to 

 the calcaire grossier and the London clay. The difference of sea- 

 bottom, clays predominating in the one and calcareous sands in the 

 other, would, even under conditions otherwise similar, develope a 

 somewhat different fauna. At the same time, amongst the fossils 

 found in this group in England and France, there are a few, such as 

 the Pholadomya margaritacea, Ostrea bellovacina, Rostellaria Sow- 

 erbii, Panopcea intermedia, &c., which rarely or never occur in either 

 country in any of the overlying strata; but as some of these species 

 range down to the chalk in parts of the Paris basin, further evidence 

 is probably necessary before we can draw exact parallels. A greater 

 number of English fossils are needed, and a more accurate compa- 

 rison of the species of the two countries is still required, but there 

 are sufficient indications to form in both countries a lower Eocene 

 group characterized by a partially peculiar fauna; and whatever may 

 be their foreign equivalents, it may I think be presumed, that the 

 strata Nos. 4 to 6 at Alum Bay and Nos. 3 and 4 at White Cliff' Bay 

 are synchronous with tlie Bognor rocks, forming together a distinct 

 and well-marked division. (See PI. IX. and the description of the 

 plate p. 252 et seq.). 



It may be objected that the fossils of the Bognor rocks are those 

 of the London clay. Some few of them no doubt are so, but as a 

 group they are perfectly distinct and singularly constant ; and it is 

 from the circumstance of these two divisions occurring in common 

 superposition in the London basin, that the fossils of the two have 

 been constantly given without distinction as London clay fossils J. 



Now if the Bognor beds were accumulated in a shallow sea, 

 any additional and thick marine deposit over them would not have 



* I have since seen this species in M. d'Archiac's collection. It appears to he 

 identical with the species I have found in the Isle of Wight, and apparently also 

 with the one from Bognor. 



f Mem, de I'Acad. Roy. de Bruxelles, vol. xii. 



X This has been much the case formerly in France with regard to the ' Lits 

 coquilliers,' the ' Glauconie grossiere,' the lower calcaire grossier and the upper 

 calcaire grossier, and renders the present question still more difficult to determine. 



