118 



These fosMls 

 imbeddcci by 

 mgradua) dc» 

 position. 



()l)jei tioa 

 answered. 



STRATA IN THE NEIGHBOURHOOD OF LONDON. 



the fossils of the English qhalk; since the following may ht 

 enumerated as occurring in this stratum. Rugous palates, 

 and though rarely, the scales and verfebrce ofjishes. Three 

 or four species of stellr^ marincE, A long saccular bivalve, 

 with an uncommonly thin shell, of which so little has beea 

 hitherto saved, as not to give a chance of gaining a know« 

 ledge of its general form or the structure of its hinge. A 

 bivalve, which approaches to a circular form, but is so thin 

 as to afford but little hope of discovering its genus. A bi- 

 valve, nearly circular, the margin turning upwards so as to 

 give it a patella or disk form, with numerous long processes 

 passing from the margin and external surface, and fixing it 

 to other bodies. A small pecten with sharp nngulated ribs, 

 not exceeding a quarter of an inch in length. A bivalve, not 

 an eighth of an inch in length, finely striated longitudinally* 

 bearing a bright poHsh, and seemingly possessing its original 

 light brown colour. Plates of the tortoise echinite^ and 

 several remains apparently of other species of this genus. 



When to these are added the remains of various echini, 

 such as conulites, cassidites, and spatangites, and the different 

 spines of echini which are found in this stratum ; and when it 

 isalsoconsidered, that the present account is drawn up almost 

 entirely from the productions of chalk cliffs of not more than 

 two miles in length, it will not be difficult to conceive, that 

 the number of these fossils is not less in the English than in 

 the French chalk. 



The state, in which these fossils are found, plainly 

 evinces, that the matrix in which they are imbedded was 

 formed by a gradual deposition, which entombed these ani-« 

 mills while living in their native beds- The fine and delicate 

 spinous projections of the shells are unbroken, and the spines 

 are still found adhering to the crustaceous coverings of the 

 echini; neither of whiqh circumstances could have occurred 

 had these bodies been suddenly find rudely overwhelmed by 

 these investing depositions, or had they been brought hith«r 

 from distant spots. 



It may be said, that the specimens possessing the cheracr 

 ters here alluded to are rare. With respect to the spinous 

 shells, however, they certainly occur often, although it is 

 almobt impossible to extricate tlieia uubroken from their 



S.urr^undiqop 



