from the Gault at Merstham. 35 
stiff, blue, sometimes sandy or calcareous clay, with layers of 
pyritous and phosphatic nodules, and occasional seams of green 
sand, which separates the Upper from the Lower Greensand. 
It is considered to be the lowest member of the Upper Cretaceous 
formation. In thickness it varies from about one hundred to 
upwards of three hundred feet, and some of the strata are very 
rich in organic remains, among which ammonites, belemnites, 
inocerami, and other mollusca, crustaceans, and sharks’ teeth 
are of frequent occurrence. At Betchworth, Dunton Green, 
Otford, and other places it is used for the manufacture of bricks 
and tiles. 
The best section of Gault is seen at Copt Point, near Folke- 
stone, where it is about one hundred and thirty feet thick. 
Here there is a complete exposure of a series of strata, and, from 
its easy accessibility, it has been selected as a basis for zonal 
subdivision by geologists, who have divided it into eleven zones. 
A glance at a geological map shows a line of Gault extending 
westward from Folkestone almost unbroken, except where cut 
through by river valleys, passing Wye, Ashford, Sevenoaks, God- 
stone, Merstham, Betchworth, and Guildford, to Farnham. Here 
it takes a southerly direction as far as Petersfield, when it turns 
eastward, passes north of Lewes, and comes to a full stop at 
Willington, near Hastbourne, thus forming an elongated basin 
enclosing the members of the Lower Cretaceous, that is to say, 
the Lower Greensand, Weald Clay, and Hastings Beds. 
The term Foraminifera is applied to an order of animals 
belonging to the Protozoa, mostly microscopic, which have 
existed, according to Dr. Carpenter, without any fundamental 
modification or advance from the primitive type from the Palzo- 
zoic period down to the present time. Although minute, the 
number of individuals is so incalculable, that vast mountain 
ranges, such as the nummulitic limestone of EHocene times, are 
very largely composed of their remains. In the Carboniferous 
Limestone, the Oolite, and the Chalk their skeletons are also 
extremely abundant. In the living state Foraminifera consist 
of a minute particle of protoplasm, or sarcode, or of an aggre- 
gation of such particles, without any distinction of parts into 
organs or tissues. This protoplasm is capable of extending any 
part of its substance into filaments, called pseudopodia, either 
for locomotion or for the purpose of obtaining food; it, moreover, 
secretes a shell, or test, which is either calcareous, or made up 
of agglutinated particles of mud or sand, or even of other shells, 
or of sponge spicules. Some forms of these shells are profusely 
perforated by minute pores (foramina), through which the pseudo- 
podia are protruded, and from this circumstance the name of the 
order is derived. 
This property of extending pseudopodia is not confined to the 
