APPENDIX. 
NOTE ON THE GEOLOGICAL HiStORY OR TURBINELLA. IN INDIA. 
By E. VREDENBURG, B.L., B.Sc., A.R.S.M., A.R.C.Sc., F.G.S., Superintendent, 
Geological Survey of India (communicated with the kind permission 
of the Director, Geological Survey of India). 
The genus Turbinella first appears in India in oligocene times, when it is repre- 
sented by a handsome somewhat nodose species with a tall stepped spire, Turbinella 
episoma Michelotti, which was first described from the same geological horizon in 
northern Italy. As we trace the successors of this fossil into formations of later age, 
they do not show the slightest indication of any approach towards the ‘“ sankh ” of 
India. The oligocene shell is at first succeeded, in miocene times, by Turbinella affinis, 
J. de C. Sowerby, whose main distinction from Turbinella episoma consists in the 
slightly more effaced ornamentation, principally on the body-whorl. The difference 
in outward appearance is so slight that it would often be difficult to distinguish 
specimens relatively of both species but for the fact that the miocene form bears five 
columellar folds instead of three as in the oligocene fossil. During the miocene, 
Turbinella afınis was succeeded by two more forms, first, a hitherto undescribed 
species which may be named T. pr&ovoidea, very closely related to T. afinis, but in 
which the distinction from T. episoma becomes much more clearly accentuated owing 
to a greater portion of the spire becoming nearly smooth, and lastly, in middle or 
upper-middle miocene times by a smooth form which corresponds so closely with 
T. ovordea Kiener, of the coasts of Brazil, that it cannot be separated from it other- 
wise than as a variety. In T. preovoidea, the columella bears only four spiral folds, 
of which the most anterior one is apt, in certain specimens, to become indistinct. In 
the fossil variety of T. ovoidea, three folds are especially well developed, a fourth 
anterior fold being always present, but often feeble. This is the only distinction 
from the living Brazilian shell in which, judging from the single specimen available in 
Calcutta, there is no indication of this fourth anterior fold. In their shape and 
ornamentation , the four Indian fossil forms constitute a connected series the evolu- 
tion of which consists principally in the gradual obliteration of the sculpture, but the 
_ spire always retains its elongate outline which is much steeper even than in the most 
elongate varieties of the living Indian species. | 
The age of the Indian fossil specimens of Turbinella ovoidea is probably not older 
than ‘‘tortonian,’’ that is middle miocene. The modern ‘‘sankh ’’ appears in a fossil 
condition in beds whose age must be at the limit of pliocene and uppermost miocene, 
along the Coromandel coast, at Karikal. The only specimen so far available from 
that formation is in a fragmentary condition and has not been figured, but is suffi- 
ciently preserved to have enabled Mr. Cossmann to refer it to one of the particular 
