IN THE MUD OF THE LEVANT. 65 



Virginia, for specimens of which I am indebted 

 to Dr. Bailey, is exceedingly rich in various 

 organisms, consisting chiefly of Polythalamia, 

 spines of Echinodermata, broken shells, and 

 calcareous shell prisms, Cytherinse, sponge spi- 

 cula, rounded sand particles, as well as small 

 angular grains of green Silica, such as we find in 

 our English greensand, and which have probably 

 been derived from the destruction of some of the 

 older strata. A Tertiary marl from New Jersey, 

 supplied to me by Professor Ansted, of the exact 

 age of which I am ignorant, presented very similar 

 results. 



London Clay. So small a portion of this 

 stratum contains anything like the amount of 

 calcareous matter found in the preceding cases, 

 that we should not expect to find the calcareous 

 animalculites in any great abundance; the Bri- 

 tish strata of this era contain so much larger a 

 proportion of aluminous and siliceous elements, 

 probably the detritus of the older rocks. Dr. 



and calcareous sand derived from comminuted shells and 

 corals. He observes, " From the most compact rock to the 

 very sand of the shore, the materials are universally fragments 

 of shells, corals, &c."— Trans. Geol. Soc. Second Series. 

 Vol. V. p. 110. 

 K 



