266 THE CRETACEOUS ROCKS OF BRITAIN. 
In the basement bed at Shouldham (7) glauconitic and 
mineral grains, with shell fragments, all of small size, are distri¬ 
buted with evenness and regularity through the amorphous 
calcareous matrix. Foraminifera are present, and the tests of 
arenaceous forms can be recognised, and, though not a predomin¬ 
ating feature, the even character of the marl throws them into 
greater prominence than usual; “ spheres ” are comparatively rare. 
Examination of the Washings. 
Shell Fragments.— In the West of England, at Bookham- and 
Maiden Bradley, these were not abundant; * they were chiefly flat 
fragments of Ostrea, Pecten, and Plicatula , with a few pieces of 
Inoceramus- shell or detached prisms. At Ventnor these prisms were 
very numerous; at Folkestone and in the Cambridge Greensand 
all shell fragments were comparatively rare, while at Shouldham 
they consisted chiefly of the remains of a small Brachiopod, the 
largest pieces being those of the stoutest part of the shell around 
the umbo. 
Fragments, apparently those of a minute Belemnite, occurred at 
Maiden Bradley. 
Spines of echinoderms occur in all except the Folkestone speci¬ 
men ; they are of minute size, and may be referred to Hemiaster 
or Pseudodiadema. 
Minute fish-teeth, coprolites and scales occurred in all of them, 
but were most numerous in the Shouldham deposit. Here, though 
not forming a very large proportion of the rock, they were more 
conspicuous than usual amongst the coarser material. 
Sponge spicules and Hexactinellid sponge-mesli occurred in all 
specimens. Tetractinellid and Monactinellid spicules were also 
observed, the former rarely, but in the Shouldham marl were 
several trifid spicules, the siliceous walls of which were entirely re¬ 
placed by limonite. 
Foraminifera.— Foraminifera are by far the most abundant 
group of Microzoa. The number of species which it was possible 
to isolate depended much on the comparative hardness of the rock- 
specimens dealt with. It must also be understood that no attempt 
was made to discover every species which occurs in each zone ; only 
those were taken which came readily and quickly to hand. It 
is believed that the chief and the most abundant forms occurring 
in each zone have been included, with such of the rarer kinds which 
came under notice from time to time. 
The Foraminifera isolated from the washings and residues (ex¬ 
cluding the Cambridge Greensand) were named by Mr. Chapman ; 
thirty-seven species and varieties are distributed as follows accord¬ 
ing to the classification of Dr. Brady : — 
* The specimens from Lulworth and Mupe Bay proved too hard to break 
up for satisfactory examination. 
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