188 UPPER, OR FLINTY CHALK. 



humeral bones, &c., are among the rarest productions of the chalk forma- 

 tion. 



Localities. Offham, Preston, Clayton*, and Brighton chalk-pits; the 

 last mentioned locality was first discovered by Geo. Cumberland, Esq. of 

 Bristol, to whose liberality I am indebted for the information. 



AsTERiA, OR Star-Fish. 



But few remains of these animals have been discovered in Sussex, 

 although they are not uncommon in the Kentish chalk. 



30. The specimens in my possession consist of a few detached ossiculae 

 oi pentagonaster semilunatus, {Org. Rem. Vol. iii. Tab. i. fig. 1,); and 

 fragments of a species that appears to be distinct from any previously 

 known. 



Fossil Echini. 



Of this order of raoUusca, numerous species occur both in a recent and 

 fossil state. They are marine animals, having a body more or less round, 

 covered with a crustaceous shell, and furnished with moveable spines ; the 

 mouth being placed beneath. The crust or covering is composed of an 

 immense number of plates, varying in form in different families, and in 

 some species amounting to nearly a thousand in one individual. It has 

 numerous perforations, through which the tentaculee of the enclosed 

 animal are protruded. These pores form bands (ambulacra) that divide 

 the shell into segments (arece), the latter being more or less covered 

 with tubercles, to which the spines are attached by strong ligaments. 

 Upon the death of the animal these ligaments undergo decomposition, 

 and the spines almost constantly fall off, a circumstance that explains the 

 cause of their being so seldom found in connexion with the shell, in a 

 fossil state. The mouth is armed with five or six triangular teeth. 



These animals feed upon crabs and the lesser kinds of shell-fish, which 



* A specimen was discovered near Clayton, many years since, by Richard Weekes, Esq. 

 of Hurstperpoint. 



