306 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



The seven species to which numbers are appended are the most 

 common, and the numbers indicate the relative abundance of indivi- 

 duals according to M. Bosquet's observations. From the above data 

 Professor Forbes infers that this Pectunculus-bed was probably- 

 formed at the junction of his perilittoral and median zones, or at the 

 depth of from 15 to 20 fathoms. There is an absence here of Ceri- 

 thia and other brackish and freshwater species. 



The next fossiliferous bed {d, section, fig. 2), separated from the 

 former by 4 feet of white sand without shells, is only 6 inches thick. 

 It consists of a shelly sand with Cerithia, below which is another bed 

 of sand without shells, and then a second layer of shelly sand with 

 Cerithia {/, fig. 2). The shells in the two beds {d and/) are 

 almost identical, but their proportional numbers differ slightly. 



Fossils in Beds d andf. White Shelly Sands with Cerithia^ at 

 Bergh. — M. Bosquet. 



Corbula pisum 



Corbulomya triangula... 



complanata 



Astarte Henckeliusiana 



Cyrena semistriata 



Lucina striatula 



Thierensii 



Venus incrassatoides ... 



Kickxii 



Cardita Omaliana 



Cardiuin tenuisulcatum 

 Limopsis Goldfussii ... 

 Pectunculus fossilis ... 



rf" 



"./•" 



1 



1 



2 



3 



1 



1 



1 



1 



2 



3 



1 





2 



2 



1 



1 



1 



2 



1 



1 



1 



1 



2 



3 



1 



1 



Pectunculus pulvinatus 



Pecten Hoeninghausii 



Paludestrina Draparnaudii... 



llissoa } Chastelii 



plicata 



Rissoina Nystii 



Cerithium subcostellatum ... 



elegans 



Pleurotoma belgica 



Buccinum Gossardii 



Voluta Rathieri 



Cy theridea Mulleri 



1 

 1 

 2 

 2 

 1 

 2 

 3 

 1 

 1 

 1 

 1 

 1 



*/" 

 1 

 1 

 3 

 3 

 1 

 3 

 4 

 2 

 1 

 1 

 1 

 1 



The numbers appended denote the relative abundance of the several 

 species, Cerithium subcostellatum (C. plicatum, Lamk.) being the 

 most common. It will be observed that the freshwater and brackish 

 water species are represented by a larger number of individuals in f, 

 or in the lower bed. Prof. E. Forbes infers that these strata were 

 formed in the upper part of his perilittoral zone, or in depths varying 

 from low tide-mark to 6 or 7 fathoms. 



In the Bergh sands the following six species are often much rolled ; 

 Cyrena semistriata, Desh., Venus incrassatoides, Nyst, Pyramidella 

 cancellata, Nyst, Rissoa plicata, Desh., Cerithium elegans, Desh., 

 and Cerithium subcostellatum, Schloth. But M. Bosquet remarks 

 that some individuals even of these species are so perfect as to appear 

 to have lived on Jthe spot, and that there is no ground for inferring 

 that such species were washed out of older beds, or that they did not 

 inhabit rivers or estuaries communicating with the sea in which the 

 white sands of Bergh were formed. 



Beneath *'/" of section, fig. 2, are white sands several feet thick, 

 without fossils, except that a few specimens of Cyprina Nystii have 

 been met with ; and there is then a break in the section at Bergh at 

 the place of the yellow sands (b, Table VIII. p. 304) which occur at 

 Kleyn Spawen and Vieux Jonc, interposed between the white sands 

 of Bergh (a. Table VIII.) and the green marls (c) of the same table. 



