Recieics — Rev. T. G. Bonney s Cambridgesliire Geology. 123 
deposits as that expressed in papers which have appeared in tliis 
Magazine. The Gault in this district is described as a pale bluish- 
grey tenacious clay, in which are concretions of iron pyrites, small 
crystals of selenite, and light brown phosphatic nodules ; its thick- 
ness at Cambridge is about 115 feet, near Hitchin 214. Its upper 
surface is uneven. The base of the Gault contains several fossils, as 
Inocerainus concentricus, Nucula pectinata, Belemnites minimus, etc. 
Kesting on the eroded surface of the Gault there is a stratum barely 
a foot in thickness, full of green grains of glauconite and black 
nodules of phosphate of lime, looking like a Sediment from the 
purer marl above ; it contains erratic boulders covered with 
Plicatula sigillina , as was pointed out by Prof. Seeley in the third 
volume of this Magazine. This bed is remarkable for the number 
of fossil fishes, Deinosaurs, Omitliosaurs, Chelonians, etc., which it 
contains ; Mollusca, Crustacea, Ccelenterata, Foraminifera, are also 
abundant. Mr. Bonney supposes the phosphatic nodules to have 
been formed by concretionary action. He regards some of the 
fossils as having been derived from the Gault. We cannot agree 
with him in calling this seam Chloritic-marl ; as the fossils proper to 
the bed are those of the Chalk-marl, and the characteristic fossils of 
the Chloritic-marl are almost entirely absent. The Chalk round 
Cambridge contains Holaster subglobosus, Inoceramus Cuvieri, etc. 
(see Seeley, Geol. Mag. Yol. I. p. 153). The Post-Pliocene de- 
posits of Cambridgeshire are described in the following order : — 
1. Boulder-clay. 2. Coarse Hill Gravel. 3. Fine Gravel of the 
Plains — this is well seen. at the Barnwell Gravel Pit ; it contains 
Cyrena fluminalis, Hydrobia marginata and Unio littoralis, all 
now extinct in England ; along with these are found existing 
species of land and fresh-water shells, and bones of Bos, Equus, 
Bhinoceras tichorhinus, Elephas, Hippopotamus, etc. ; flint imple- 
ments have also been found. A deposit of gravel at March contains 
marine shells. 4. Older Peat. 5. Buttery Clay. 6. Ne wer Peat. 
Next follow five appendices to the work. The first contains an 
account of the Upware Sections, with which the readers of this 
Magazine are well acquainted. The second, an account of the Boslyn 
Pit, Ely, reprinted from this Magazine. Third, a short account of 
the Hunstanton Red Rock, which Mr. Bonney considers probably 
to represent palseontologically the Cambridge Greensand. Fourth, 
on the Water Supply of Cambridge, which is derived from three 
sources: 1. Old river gravels : 2. From springs at the base of the 
Lower Chalk ; 3. From artesian wells driven through the Gault iuto 
the Neocomian Sands from 100 ft. to 150 ft. deep. Fifth, on the 
Building Stones, etc., employed in Cambridge — the white bricks 
from the Gault ; red bricks of St. John’s College from London Clay 
of Suffolk ; Magnesian Limestone, the lower part of King’s College 
Chapel ; Inferior Oolite from Aislaby, near Whitby, great room of 
University Library and Woodwardian Museum ; Lincolnshire Lime- 
stone, King’s College Chapel, New Courts of St. John’s and Trinity, 
etc. : Batli Oolite, University Press and Observatory ; Portland 
Oolite, Senate House, fa(jade of University Library, Fitzwilliam 
