VIII.—Note On Some Post - Tertiary Mollusca From Ceylon

Extract

Some marine shells, associated with crab-remains,1 Balani, and small thread-like annelid tubes, from the Post-Pliocene deposits of north-eastern Ceylon, have been entrusted to me for determination by Dr. H. Woodward, F.K.S. They were collected by Mr. A. K. Coomaraswamy, B.Sc, Director of the Mineralogical Survey of Ceylon, and his description of the deposits containing the fossils forms the preface of this communication. Lithologically it is observable that there are two sets of specimens-those that occur in hard, water-worn nodules of clay, and others that were obtained from soft, dark, clayey beds found in situ. The fossils found in the clayey material may perhaps be rather older than those found in the nodules, but as two of the shells are common to each, viz. Placuna placenta and Potamides fluvialilis, it is certain that no great distinction in age is to be recognised.

An examination of the species represented in the collection goes to prove that they belong to the existing fauna of the Indian Ocean, being similar to the life which is found in the creeks and back-watersof that sea, and consequently bearing a littoral or an estuarine facies.

It is interesting to know of the presence of corresponding Post-Tertiary deposits crowded with shells forming the coastal areas of the Madras Presidency of India, particularly at Pondicherry, Cuddalore, Tangore, etc., for the history of which we are mainly indebted to the late Mr. H. F. Blanford (Mem. Geol. Surv. India, 1862, vol. iv, pt. 1, pp. 192,193). So numerous are the mollusca of these beds that they are utilised by the natives for the manufacture of lime.