158 
FOSSILS OF THE MARL. 
iron pyrites ; the greater part of the marl fossils 
have acquired a ferruginous colour from this mine- 
ral. 
4. Clay slate. The occurrence of this substance 
in the marl is clearly accidental, having been de- 
rived from some regular bed of argillaceous slate of 
anterior formation to the chalk marl. The only 
examples hitherto discovered were imbedded in 
the marl at Southerham, near Lewes ; the largest is 
about two inches square, and nearly half an inch 
thick : the edges are sharp, and the specimen ap- 
pears to have suffered but little from attrition. 
ORGANIC REMAINS. 
The grey Chalk marl, in its course through Sus- 
sex, abounds in organic remains, which differ both 
in their nature, and in the mode of their preserv- 
ation, from those of the superincumbent bed of 
lower chalk, and of the gait beneath. 
AmmonitcB, nautili, j^ectenitce, and inocerami are 
the most common productions of the pits near Lewes : 
which also contain turrilitce, scaphitcB, hamitcB, &c. 
These remains of testacea very rarely exhibit any 
vestige of their original shelly covering, but consist 
of casts of indurated argillaceous limestone, of an 
ochraceous or a ferruginous colour, more or less 
distorted by compression. Fish and Crustacea are 
rare : zoophytes related to the alcyonia and spongim 
are not of unfrequent occurrence. Echini are not 
abundant. Wood, in the state of that described as 
occurring in the chalk, is occasionally met with : 
and very rarely, traces of confervse. 
