104 MESSES. JFKES-BROWNE AND SCANES ON THE [Feb. TpOI, 



(5) Yery fine whitish siliceous earth or silt, too fine to be 

 called a sand, containing large irregular masses of light-grey chert, 

 which breaks into flattish slabs and angular pieces ; these chert- 

 masses are often 12 or 18 inches bigh, and are so distributed 

 that in places the bed consists as much of chert as of soft silt. 

 Crushed specimens of Holaster Icevis, and broken fragments of Pecten 

 asper and other shells, are common here. The thickness of this bed 

 is about 3 1 feet, but the silty portion is divisible into three bands 

 which differ slightly in composition. 



The upper band (12 inches thick) effervesces with acid, and is 

 therefore somewhat calcareous. The residue breaks up with slight 

 pressure, and, when washed, shows small quartz-grains to which 

 adheres much dull white colloid silica ; there are also many sponge- 

 spicules, many small dark grains of glauconite, and some flakes of 

 silvery mica : the finest part seems to consist chiefly of globular 

 silica, mica, and sponge-spicules. 



The next 12 or 13 inches may be described as a very fine, compact, 

 silver-grey silt, composed of fine quartz-sand, colloid silica, and 

 mica-flakes, with many spicules of Lithistid sponges and grains of 

 yellowish-green glauconite ; glauconite also occurs in the irregular 

 hollows of the spicules. 



The lowest part of the bed (18 inches) is a fine sand, very similar 

 to that above it, but with less organic silica and more glauconite. 



Bed 6 is a fine light-grey glauconitic sand, showing streaks 

 or laminae of slightly different tints, owing apparently to a varying 

 proportion of glauconite-grains. It is divisible into two bands, 

 the upper 8 inches being yellowish-grey, and consisting of minute 

 even-sized quartz-grains with a fair sprinkling of glauconite-grains 

 of nearly the same size as the quartz. This band weatbers to a 

 brownish-yellow, owing to the oxidation of the glauconite. It 

 contains many broken shells, and some more or less perfect, among 

 which the following; have been identified : — 



Ostrea canaliculata. 

 Pecten Galliennei (1). 

 Neithea (Bquitosiata. 



quadricostafa. 



Plicatula sigiUina. 



Exogyra hcdiotoidea. 

 Cardiaster fossarius. 

 Cottaldia PenetHcs. 

 Glyphocyphus radiatus. 

 Ossicle of starfishes. 



The middle part of the bed (about 12 inches) is a fine greyish- 

 white sand, with much colloid silica both scattered and in nests, 

 and only a few small grains of glauconite. Below this are 6 inches 

 of fine spiculiferous sand, consisting of a mass of broken sponge- 

 spicules (chiefly Lithistidse), the hollows and canals of which are 

 filled with glauconite. 



There are very few cherty concretions in these lower layers, and 

 no fossils have been found in them, except siliceous sponges and 

 sponge-stems and pieces of Serpula {? annulata), 



(7) This is a bed of cherty material forming a continuous 

 layer nearly 2 feet thick, but it breaks up into large irregular 

 blocks. The outer portions are a greyish sponge-rock, the inner 



