EXPLANATION OF PL ATE XX. 



The line drawn next to or between the different views of the shells shows 

 the actual length of the specimen. 



Figs, la, ih, ic. — Dostia platyconcha , sp. nov., shell of the type- 

 specimen. 



,, 2. — Opercula of the Gangetic species of Dostia, Y. 2. 

 {a) D. cornucopia (Benson). 



(b) D. depressa (Benson). 



(c) D. platy concha, sp. nov. 



The opercula are drawn from actual specimens. That oi D. p/ntj'coiicha 

 is always smaller than those of the other two species ; but that of D. cornu- 

 copia is not always smaller than that of D. depressa. 



,, 3. — Littorina subintermedia, Nevill, shell of a specimen from 

 the Gangetic Delta. 



,, 4. — Littorina delicatula, Nevill, shell of a specimen from the 

 Gangetic Delta. 



,, 5. — Stenothyra echinata, sp. nov., shell of the type-specimen. 



,, 6. — Stenothyra soluta, sp. nov., shell of the type-specimen. 



J, 7. — Lateral view of an expanded living individual of Assi- 

 minea francesiae (Gray). 

 8, — Melania [M ainwaringia) paludomidea, Nevill, shell of a 

 specimen from the lower reaches of the Gangetic 

 Delta. 



,, 9. — Nassa ennurensis var. depauperata , nov., shell of the type- 

 specimen. 



,, 10. — Ringicula caeca, sp. nov., shell of the type-specimen. 



,, I r . — Auricula translucens , sp. nov. , shell of the type-specimen. 



