310 NATURAL SCIENCE [November 
The evidence of the foraminifera points to 700 fathoms for the 
depth of this deposit. 
Zone IX,—A dark blue-grey marl. Globigerina cretacea is found 
in some abundance, and from theuce through the succeeding zones 
increases in quantity until near the top of the Gault. The deposit, 
compared with recent accumulations, might be termed a grey terri- 
genous ooze, 
The foraminifera indicate a depth of 910 fathoms. 
Zone X—A pale green-grey marl. This zone perhaps more 
nearly foreshadows conditions which obtained in the Chalk-marl 
than any of the others. The proportion of calcareous matter is very 
large (as much as 457); at 45 ft. from the top—in Zone XI. it 
was 367%; the Chalk-marl of Eastwear Bay at 10 ft. above the 
‘Chloritic’ marl gave 674% of calcareous matter. The conditions 
existent then in Zone X. must have been favourable for calcareous 
shelled organisms. Here particularly we obtain a great variety 
of the strong shelled and costate forms of the genera Nodosaria, 
Frondicularia, Marginulina, and Vaginulina ; and it was from this 
zone more especially that the redundant and abnormal forms described 
in my systematic papers (see Part X. Foraminifera of the Gault of 
Folkestone) were obtained. This deposit may be classed with those 
of modern date as a grey terrigenous ooze, and had a probable depth 
of 900 fathoms. 
Zone XI.—This bed, measured up to the base of the green-sand 
seam, is a pale grey marl. Globigerina cretacea considerably increases 
in abundance, and attains its maximum profusion at 45 ft. to 25 
ft. below the top of the Gault, as well as in the next zone at 20 ft. 
from the top. 
This bed can be compared with a grey terrigenous ooze, and 
appears to have been deposited in 870 fathoms. 
Zone XIT.—A glauconite-marl. A noteworthy point about this 
deposit is that the glauconite casts have been formed at a less depth 
than that at which the associated foraminifera lived ; for the foramini- 
feral tests seen intermingled with the glauconite casts in the wash- 
ings undoubtedly belong to a later period than the originals of the 
casts themselves; these remarks also apply to the microzoic fauna of 
the green-sand seam of Zone I. 
This deposit is to some extent comparable with the glauconite 
muds, and its depth is indicated as 820 fathoms. 
Zone XITI.—A pale grey marl, perhaps to be compared with the 
grey terrigenous oozes of modern deposits. 
The foraminifera indicate a depth of 850 fathoms. 
It is here necessary to refer to a few points in explanation of 
the evidence afforded by the foraminifera alone, as regards the depeh 
of sea in which these organisms lived. 
