EEN3TEAD — 0I«^ THE GEOLOGY OF MAIDSTONE. 



339 



Museum. Your tooth belongs to the species continuus, so called on 

 account of the enamel being continued from top to bottom ; the den- 

 tine is compact, and has been resolved by decomposition into a series 

 of superimposed hollow cones ; the pulp-cavity is confined to the base 

 of the crown, by which it differs from the teeth of the Hypsodon." 



A paper was read before the Geological Society on the peculiarity 

 observed in this layer, of the cavities of the shells being filled with 

 moUuskite. In the blocks of " firestone " or Upper Greensand, whic1i< 

 are visible at low-water along the shore at Southbourne, Sussex, small 

 concretions of phosphate of lime are thickly interspersed amongst 

 the fossil shells. In my earliest geological researclies along the 

 Sussex coast, these fossil bodies particularly arrested my attention ; 

 but I failed to obtain any clue to their origin until the important 

 memoir on coprolites, by Dr. Buckland, pointed out the right path 

 of inquiry, and gave the clue to the formation of molluskite from the 

 animal matter of the shell-fish. 



That a large proportion of these phosphatic concretions and nodu- 

 lar masses are the mineralized egesta of fishes and other marine ani- 

 mals, there can be but little doubt, although it is rarely, if ever, possible 

 to detect any traces of the convolutionary form of the intestines 

 through which they have passed, and which are always more or less 

 strongly impressed on the coprolites of the Chalk, Wealden and Lias. 

 In the Southbourne rocks, however, instances are very common in 

 which the phosphatic matter occurs as casts of shells, especially of 

 the genera Venus and Trochus, which abound in the firestone beds ; 

 the substance of which casts appears, therefore, to have originated 

 from the soft bodies of the mollusca that died within them. In 

 Sussex, these phosphatic nodules are very abundant in the layers 

 of the firestone which form the junction with the Gault. They are 

 also frequent in the beds of Gault at Eingmer and jN"ortington, near 

 Lewes, and in the Surrey strata. They also occur at Folkestone, in 

 Kent. At page 296, 1 also mentioned the occurrence of similar nodules 

 at New Ilythe. The late Dr. Fitton, in his elaborate memoir ' On 

 the Strata below the Chalk ' (Trans. Geol. Soc. vol. iv. pi. 2, p. Ill), 

 has given a description and analysis of those coprolitic nodules and 

 concretions which occur at Folkestone. He says, " They resemble 

 coprolites in their chemical composition, though no traces of animal 

 structure are apparent in them. They sometimes enclose portions of 

 shells, but no fragments of bones or scales of fishes.* In some cases 

 they are of very irregular figure, surrounding or incorporated with 

 fossil remains, the interior of which is filled witli matter of the same 



* III some few cases T have found fisli scales and small teeth of sharks in those at 

 Folkestone. Sliell-casts, especially of Dentalia, are very common ; and one very important 

 layer in the Gault at Folkestone is entirely formed of the more or less hrokeu casts of 

 ammonites. Portions of wood aie extrcuicly common in the nodides forming the junction 

 bed of (iault and Lower Greensand there. Fossil oyster-shells and serpula are very coiii- 

 nionly attached to their exterior surfaces, showing they were consolidated whilst lying 

 at the bottom of the Gault and Greeusand seas, and before they were embedded. — 

 Ed. Geol. 



