The Non-Marine Mollusca of Clacton-on-Sea

Abstract

An account of the non-marine mollusca of Clacton based on the known collections was published by us in 1897,1 when we were able to record sixty-one species; but of these fifteen were unconfirmed records. Since then Dr. Frank Corner has kindly sent us a small series principally obtained from the estuarine bed, while the extensive collection of the late Dr. Henry Woodward has passed into our keeping. From this additional material we were able to raise the total number of known species to sixty-seven. We are greatly indebted to Mr. S. Hazzledine Warren for placing at our disposal the results of his systematic exploration of these beds. The number of known species is now eighty-two, the longest list from any English Pleistocene deposit. One species, Vertigo pusilla Miiller, although recorded by S. V. Wood, we have omitted, since there are no examples extant. In the following table we have indicated in the first column the results of previous work, while the remainder show the frequency of each species in the various layers recognized by Mr. Warren. From the estuarine bed three species were obtained, namely:— Paladilhia radigueli (Bourguignat) common, Vivipara diluviana (Kunth) rare, Corbicula fluminalis (Müller) rare, as well as two marine species, namely:— Scrobicularia plana (Da Costa). Cardium edule Linn. Thus sixteen new records are added to the list, while eight known species were not represented in Mr. Warren's collection. Notes on the Species. L imax .—Hitherto no species of Limax has been recorded from Clacton. Why this genus should be so rare