264 
ELEMENTS OF GEOLOGY. 
with layers of concretions called septaria, which abound chief¬ 
ly in the brown clay, and are obtained in sufficient numbers 
from sea-cliffs near Harwich, and from shoals off the coast 
of Essex and the Isle of Sheppey, to be used for making Ro¬ 
man cement. The total number of British fossil mollusca 
known at present (January, 1870) in this formation are 254, 
of which 166 are peculiar, or not found in other Eocene beds 
in this country. The principal localities of fossils in the Lon¬ 
don clay are Highgate Hill, near London, the Island of Shep¬ 
pey at the mouth of the Thames, and Bognor on the Sussex 
coast. Out of 133 fossil shells, Mr. Prestwich found only 20 
to be common to the Calcaire Grossier (from which 600 spe¬ 
cies have been obtained), while 33 are common to the “ Lits 
Coquilliers” (p. 275), in which 200 species are known in 
France. 
In the Island of Sheppey near the mouth of the Thames; 
the thickness of the London Clay is estimated by Mr. Prest¬ 
wich to be more than 500 feet, and it is in the uppermost 50 
feet that a great number of fossil fruits were obtained, being 
chiefly found on the beach when the sea has washed away 
the clay of the rapidly wasting cliffs. 
Ficr. 205 . Mr. Bowerbank, in a valuable 
publication on these fossil fruits 
and seeds, has described no less 
than thirteen fruits of palms of the 
recent type Nipa^ now only found 
in the Molucca and Philippine Isl¬ 
ands, and in Bengal (see Fig. 205). 
In the delta of the Ganges, Dr. 
Hooker observed the large nuts of 
Nipa fruticans floating in such 
numbers in the various arms of that 
great river, as to obstruct the pad- 
_ ^ ^ dle-wheels of steamboats. These 
Fossil fruit of palm, from Sheppey. COCOanut 
tribe on the one side, and on the other to the Pandanics^ 
or screw-pine. There are also met with three species of 
Anona^ or custard - apple; and cucurbitaceous fruits (of 
the gourd and melon family), and fruits of various species 
of Acacia, 
Besides fir-cones or fruit of true Coniferae there are cones 
of Proteaceae in abundance, and the celebrated botanist the 
late Robert Brown pointed out the affinity of these to the 
New Holland types Petrophila and Isopogon, Of the first 
there are about fifty, and of the second thirty described spe¬ 
cies now livinsr in Australia. 
Nipadites ellipticus, Bow. 
fru 
