LOW Eli CHALK—Ml'OROGE A I’HlC STRUCTURE. 285 
of glauconite which are probably casts of spicular canals are some¬ 
times common. Dr. Hume* has recognised a single Lithistid 
spicule in the Chalk-Marl of Culver Cliff, Isle of Wight, and here 
the Hexactinellidce are represented also. 
Hexactinellid mesh occurs again in the Chalk-Marl of Norfolk 
and in the Sponge Bed of Hunstanton, and single spicules (of un¬ 
certain affinities) are also to be seen in thin sections of this rock. 
Here, however, the siliceous wall of the spicule is replaced by cal- 
cite. None occur either in washings or residues. In the Chalk 
Marl just above the Cambridge Greensand at Arlesey several frag¬ 
ments of Hexactinellid mesh occurred, the silica either replaced 
by or coated with limonite. 
Coprolites —The chalk of Mupe Bay, up to 20 feet above the top of 
the glauconitic marl, contains minute phosphates of various shapes. 
They are not very numerous. Some are elongated cylinders with 
annular ring-like markings ; these are now regarded as the excreta 
of fishes ; others, shaped something like an acorn, remind one 
of the larger examples found in the Grey or Middle Chalk ; others 
again are small ovoid bodies. The last occur in almost all 
marls. Fish teeth and scales are rare. 
Clear, round, reddish-brown grains occur in nearly all specimens 
near the base of the Marl, but are less common at the summit. 
They are referred to by Dr. Hume,I who says : “ M. Laxne has carried 
out some analyses which lead him to the conclusion that these were 
probably glauconite, and that the color is due to alteration, a 
view which would also be strengthened by the similarity of occur¬ 
rence in both cases.” The external appearance of these grains is 
smooth and glassy; in the chalk of Mupe Bay similar material 
occurred in elongate form with a central constriction. Barely 
grains of similar shape, white and glassy or with slight cloudiness, 
were observed. 
Foraminifera .—Including seven species already recorded from 
the Chalk Marl of Folkestone by Mr. Chapman f, the total number 
obtained from this zone is 116. A list of these species and their 
distribution will be found on p. 329. They were identified by Mr. 
Chapman, and according to Dr. Brady’s classification belong to 
the following genera and families : — 
* Chemical and Micro-Mineralogical Researches on the Upper Cretaceous 
Zones, by W. T. Hume, p. 21. 
t Ilume, op. cit p. 24. 
+ The Foraminifera of the Gault of Folkestone, Journ. Roy. Mic. Soc. 
(1898), page 40, 
