need help for bivalve

[helmetapointe]

Somebody can help to id this bivalve from kerala,s.w.india ? 55.0 mm }ty  <img src="images/smiley/smile.gif" alt="" border="0" />
<a href="http://www.noelshack.com/" target="_blank"><img src="http://www.noelshack.com/up/aac/4forumcopy-8bae3d1762.jpg" alt="http://www.noelshack.com/up/aac/4forumcopy-8bae3d1762.jpg" style="border:0" /></a> <a href="http://www.noelshack.com/" target="_blank"><img src="http://www.noelshack.com/up/aac/p11506184forum-80fb76b15.jpg" alt="http://www.noelshack.com/up/aac/p11506184forum-80fb76b15.jpg" style="border:0" /></a>

[paul monfils]

Hecuba scortum, family Donacidae