AQUATIC MOLLUSCS OF THE INLE LAKE AND 

 CONNECTED WATERS. 



By N. Ann AND ALE, B.Sc, F.A.S.B., Director, 

 Zoological Survey of India. 



(Plates X— XIX.) 



TABLE OF CONTENTS. 



Pag e. 

 Introduction ... ... ... ... ... ... 103 



Part I. — Systematic. 



Succineidae ... ... ... ... ... 104 



Lininaeidae ... ... ... ... ... 10.5 



Melaniidae ... ... ... ... ... 114 



Hydrobiidae ... ... ... ... ... 116 



Viviparidae ... ... ... ... .... 12.3 



AmpuUariidae ... ... ... ... ... 137 



Unionidae ... ... ... ... ... 138 



Cyrenidae ... ... ... ... ... 141 



Part II. — Palaeontological. 



Cave-deposits ... ... ... ... ... 143 



Lake-deposit ... ... ... ... ... 143 



Superficial deposits ... ... ... ... 144 



Part III. — Geographical. 



Living MoUusca ... ... ... ... ... 145 



Fossil and subfossil Mollusca ... ... ... 147 



Conclusions ... ... ... ... ... 14S 



Part IV. — Plasticity and evolution. 



Pulmonata ... ... ... ... ... 148 



Prosobranchiata ... ... ... ... ... 155 



Pelecypoda ... ... ... ... ... 168 



Conclusions ... ... ... ... ... 169 



List of species, sliowing approximate age, etc. ... ... 177 



Literature ... ... ... ... ... 179 



Note on the Palaeontology of the Inle Mollusca bj' E. Vredenburg 182 



INTRODUCTION. 



The followino paper is based on the collection of Mollusca made 

 in the Inle Lake and the surrounding district by Dr. F. H. Gravely 

 and myself in February and March, 1917. 



The district is one of great interest to students of the freshwater 

 Mollusca because it is one of those in which the fauna, apparently 

 isolated for a long period, has proved extraordinarily plastic, with the 

 result that large numbers of peculiar forms have been evolved. It 

 is not necessary here to describe its physical characters as this has 

 already been done in the Introduction to the volume, but there are 

 a few points that it is of importance to remember. In the first place, 

 the Inle Lake, which lies on the Shan Plateau at an altitude of 3,000 

 feet above sea-level, occupies a basin that it has dissolved for itself out 

 of limestone. Its water, therefore, contains abundant salts of lime 



