9 
On the Occurrence of Ostrea gryphoides Schlotheim 
in Calcutta. 
By J. Cocein Brown, O.B.E., D.Sc, ee 
G eolozical Survey of India 
(Published with the permission 4 Director, Geological Survey 
of India.) 
Our knowledge of the deeper strata underlying Caleutta 
is derived from the results of one boring, sunk to a depth of 
481 feet in Fort William during the years 1835 to 1840, for 
although several holes have been drilled within recent years, 
Some to considerably greater distances than this in the search 
for sub-artesian water, the lo ogs of the bores do not appear 
to have been published and its certainly not found their 
way into the archives of the Geological Survey of India. 
In the Fort William boriag no trace of marine deposits 
was detected, indeed a s Mr. R. D. Oldham 
has awl out,— thes appears every 
on for believing that the beds traversed, 
from top to bottom of "the borehole. had been deposited either 
by fresh water, or in the neighbourhood of an estuary. Ata 
The shit had iHliam 
mean tide level, and again at 382 feet, beds of peat with wood 
were found....Moreover, at considerable depths, bones of 
terrestrial mammals and fiuviatile reptiles were found, but 
the only fragments of shells —— at 380 feet, are said to 
have ae of fresh water spec 
1904, while treviivein were in progress for the foun- 
thee © dations of a new building in Clive Street, 
oe Oysters in Clive an oyster band, a few inches in 
Stre wa eet with about 5 feet seg surface 
lev was examined by t te Mr. 
EK. W. Vredenburg of The Geologea Survey of India! He 
reported that the stratum covered a space of at least 100 feet 
square, that one foot, or a little less, of brown mud intervened 
between the top of the oyster bed and the bottom of some old 
brick foundations, and further, ye? ag sega ae stratum 
consisted of black mud. The o were recog by 
Col. A. W. Alcock, F.R.S., at srt ace ‘Superintendent of the 

D. Oldham: ‘‘ A Manual of the Geology of India,’’ pp. 432 
433 (1803), 

V. Vredenburg: ‘* Rece bed ia 
Caloutia.” Rec. Geol, Surv. Ini., Vol. NXT a a L176 fon. 
