1918.] N. Annandale : Molhiscs of the Inle Lake. 



145 



The other kind of superficial deposit in the He-Ho basin is of a peaty 

 or calcareous nature, the calcareous parts taking the form of narrow 

 ridges of tufa in the masses of peat. No difference could be detected 

 between the species from the tufa and those from the peat, but there is 

 evidence that the shells had in some instances been carried about for 

 short distances by the streams whose beds are represented by calcareous 

 ridges,^ and it is probable that all are not precisely of the same age. 

 Specimens of Melania haccata and of Planorhis exustus in some cases 

 retain their epidermis, which has entirely disappeared from the other 

 shells. The fresher specimens were as a rule found embedded in tufa. 

 The species are : — 



Planorbis exustus. 

 Melania tuherculatu. 

 Melania haccata elongata. 

 Hydrohioides vassa distoma. 



Taia intermedia. 

 Taia lacustris. 

 Taia analoga. 

 Corhicula nottlimji. 



These species and races, with the exception of Taia intermedia, 

 T. lacustris and T. analoga, still survive. The shells are probably not all 

 contemporaneous but the deposits as a whole evidently represent the 

 last stages of the old He-Ho lake, when it had already become a mere 

 swamp and parts of its bed were practically dry, with small streams 

 winding through them. I class the shells as subfossil. 



In this section of the paper mention should also be made of the 

 extinct phase of Limnaea shanensis dredged from the bottom of the 

 Inle Lake. It was the only fossil or subfossil shell found in this position. 



Part III.— GEOGEAPHICAL. 



I. Living Mollusca. 



In considering the geographical relationships of the fauna of the Inle 

 Lake it is necessary to consider also those of the non-lacustrine aquatic 

 fauna of connected waters. In the following list I have included the 

 names of all the species and races of Mollusca found in streams, pools 

 and marshes in both the Inle and the He-Ho basins, as Well as those of 

 the species and races that live in the lake. The fossil and subfossil 

 forms of the district I will consider separately. 



Gastropoda. 



Siiccinea indica. 

 Limnaea andersoniana. 

 Limnaea sh a ne nsis. 

 Limnaea mimctica. 

 Planorbis exustus. 

 Planorbis velifer. 

 Planorbis trochoideus. 

 Planorhis calathu-s. 

 Planorhis caenosns. 

 Melania tuberculata. 

 Melania terebra. 

 Melania baccata elomjata. 

 Paludomus ornata. 



Hydrohioides nassa. 



Hydrohioides nassa lacustris, 



Hydn/hiiiidcs physcus. 



Hydrohioides avarix. 



Hydrohioides nana. 



Amnicola alticola. 



Vivipara lecythis. 



Taia naticoides. 



Taia theohaldi. 



Taia shanensis. 



Taia elitoralis. 



Taia intha. 



A mpv llaria iidnkleyi. 



^ See the Introduction to this volume, p. 5. 



