ANNIVERSARY ADDRESS OF THE PRESIDENT. xlix 
with the clays of Barton, and the clays and sands of Bracklesham in 
the Hampshire tertiary district, but that it was of older date, 
occupying a lower position in the tertiary series. 
Upon: comparing the fossil remains of the calcaire grossier with 
those of the London clay, Mr. Prestwich finds that not quite four per 
cent. of the testacea discovered in the former have been observed in 
the latter, and that even this small number is of little chronological 
value ; for, with few exceptions, all of these have a wide vertical 
range in the Eocene series of France. The general character of the 
testacea is stated to differ, and if the fishes, plants, foraminifera, crus- 
taceans and zoophytes be compared, the same marked distinctions are 
found throughout. 
In comparing the tertiary deposits of Hampshire with those in 
the so-called London basin, Mr. Prestwich notices sands and mottled 
clays as the lowest, presenting a remarkably uniform mineral charac- 
ter, the beds formed of red mottled clay and of siliceous light-coloured 
sands, varying in proportions, and non-fossiliferous. Above this de- 
posit there is, in Hampshire, a thick and important mass of fossiliferous 
brown and grey clay, well-seen in Alum and White Cliff Bays, 200 
feet thick at the former, 300 feet at the latter, and in the well at 
Southampton, therefore thickening gradually in its range northward 
and eastward. To this accumulation Mr. Prestwich had formerly 
assigned the name of “the Bognor beds.’? In the London district 
the mottled clays are covered by a similar accumulation, and the 
latter in both districts is described as reposing upon a peculiar 
water-worn and irregular surface of the former. The pebble beds 
and sands at the base of the London clay are pointed out, as also the 
calciferous and usually fossiliferous band at Hedgerly and other 
places around London and near Salisbury and Southampton. It is 
shown that, where the superposition can be traced in the London 
district, the pebble beds are subordinate to sands, chiefly yellow, but 
sometimes green and dark gray, laminated with clays, with subordi- 
nate sandy clays. These deposits constitute the bulk of the London 
clay, the upper beds brown, and usually sandy near the top. As 
regards thickness in the London district, it is 320 feet near Odiham 
and about 400 feet at Highgate and Hampstead. Thus from the 
lithological structure alone the author concludes that the Bognor 
_ beds of Hampshire and the London clay are geologically the 
same. 
Mr. Prestwich then examines the fossil contents of the beds, and 
finds that, taking the 390 described species of Testacea, of which 133 
occur in the London clay near London, 193 in the beds at Brackle- 
sham Bay, and 209 at Barton Cliffs, only 35 species are common to 
all these localities, 8 species common to London and Bracklesham, 11 
to London and Barton, and 55 to Bracklesham and Barton. Adding 
to these fossil remains those of the crustacea, fishes, reptiles and 
plants peculiar to the London district, he concludes that the London 
clay is not synchronous with those of Bracklesham and Barton, but, 
viewing its relations with the mottled clays, lower than the former, 
and still lower than the latter. The author would not restrict the 
VOL. IV.—PART I. d 
