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DR. Gr. J. HINDE ON BEDS OF SPONGE-REMAINS IN THE 
which the deposits occur. On the death of the animal, the soft tissues by which its 
skeleton was held together would rapidly decay, and its individual particles would 
thus become detached from each other and scattered over the surface of the sea- 
bottom. As a result of this, the fossil sponge-beds consist of a heterogeneous mixture 
of the skeletal spicules of various kinds of sponges. Under exceptionally favourable 
conditions of preservation the minute spicules are now met with in a loose, detached 
condition, not unlike that in which they may be supposed to have been present at the 
sea-bottom soon after the death of the animal, but, as a general rule, they are now 
amalgamated with the inorganic materials of the deposits into hard beds of rock, and 
they have suffered partial or complete solution and replacement by calcite, glauconite, 
and iron-peroxide. 
I. The general Characters of the Sponge-Beds in different Localities. 
It is generally known that the principal outcrops of the lower and upper greensand 
occur round the borders of the Wealden area in the counties of Surrey, Kent, Sussex, 
and Hampshire. Both divisions are well represented in the Isle of Wight, and, 
farther westward, the upper greensand is exposed in Dorsetshire, Wiltshire, Somer¬ 
setshire, and Devonshire. I propose first to refer to the sponge-beds of the lower 
greensand, and to begin with those on the north-western margin of the Weald, in the 
county of Surrey. 
Haslemere .—In the mostly unconsolidated sands of the district round this town the 
sponge-beds occur as thin layers of porous siliceous rock of a grayish or yellowish tint. 
The beds are from one to three inches ('025 to '075 m.) in thickness. Their exposed 
surfaces are usually rough and harsh to the touch and uneven. When somewhat 
weathered the surfaces of the beds exhibit an agglomeration of sponge-spicules, which 
are thickly intermingled together, without arrangement of any kind. The spicules 
are cemented together by siliceous material, but the cement is in small proportion to 
the mass of spicules. The spicules are less clearly shown in the interior of the beds 
where they are concealed by the matrix, but it is evident from exposed fractured 
surfaces that the beds throughout are similarly composed of masses of spicules resem¬ 
bling those shown on their upper sui'faces, and that there is but a slight admixture 
of the quartz-sand grains which compose the strata inclosing the sponge-beds. In a 
sand-pit a short distance to the north-west of Haslemere, a sponge-bed occurs in an 
unconsolidated condition, and the sponge-spicules are disseminated loosely in the sand, 
perfectly free from each other. This bed afforded abundant material for the study of 
the spicules, which are now partly in the state of chalcedony and partly of crystalline 
quartz. It is a curious circumstance that though loose in the bed, many of the larger 
spicules have been evenly fractured in three or four places, and the fractured portions 
have been re-cemented together, sometimes with a slight lateral displacement 
(Plate 42, figs. 6a, b). 
