Non-marine Mollusca are extremely rare in the Pliocene deposits of this country, which fact must always be a matter of regret to the Palæontologist, since they are of the utmost importance in connexion with the origin of our present fauna. Unfortunately, in addition to their rarity, they are often decorticated or fragmentary, whence no doubt the differences in opinion as to their correct determination. A re-examination of all the available material has convinced us that there is still much to be done before it will be possible to reach finality. In these matters so much depends on one's standpoint. If one starts with the preconceived idea that the Pliocene shells must be identical with the recent forms, it is easy enough to identify them, even if one has to go to Japan or Greenland to find its present habitat. If, on the other hand, one considers it better to study carefully the results of recent work on other branches of the fauna, it is obvious that different results will be arrived at. Hence we are quite prepared for any differences of opinion as to the correctness of our views or the wisdom of creating four new species, as we now venture to do.