EXPLANATION OF PLATE XX. 



Indian species of Cyres'a. 



All the figures are direct photographs of the right valves of 

 specimens in the Indian Museum, reduced to | the natural size. 



Cyrena bengalensis, Lamarck. 



Fig. I.— Medium sized shell from the Sunderbans in the 

 Gangetic Delta. 

 ,^ 2.— Adult shell from the Salt Lakes near Calcutta. 



Cyrena siamica, Prime. 



Fig. 3. — Medium sized shell from Rangoon, Burma. 



4. . , the Nicobar Islands. 



,5. .. .." ;, ,, Cochin-China. 



Cyrena impressa, Deshayes. 

 Fig. 6. — Medium sized shell from Ratnagiri, near Bombay. 

 ,, 7. — Adult shell from the same locality. 



Cyrena proxima, Prim.e. 



Fig. 8— Medium sized shell from the Mergui Archipelago. 

 ,, 9. — A smaller shell from the same locality. 



Cyrena tennentii, Hanley. 

 Fig. 10. — A full-grown shell from Ce\lon. 



Cyrena ceylonica (Chemnitz). 

 Figs, ii — 13. — Shells of different sizes, all from Ceylon. 



Cyrena galatheae, Morch. 



Fig. 14. A young shell from the Andaman Islands. 

 Figs. 15, 16.— Medium and large sized shells from the Have- 

 lock Island in the Andaman group. 



Fig. 17. — A full-grown specimen from the Trinkat Island in 

 the Nicobar group. 



