Need help identifying 4 shells

[jmom]

My son and I have been searching online and in guide books, trying to identify these four shells for his school project. Would someone be able to help us?

Thank you in advance for your help!

<a href="http://img200.imageshack.us/i/img7023vm.jpg/" target="_blank"><img src="http://img200.imageshack.us/img200/4561/img7023vm.th.jpg" alt="http://img200.imageshack.us/img200/4561/img7023vm.th.jpg" style="border:0" /></a>
<a href="http://img138.imageshack.us/i/img7024w.jpg/" target="_blank"><img src="http://img138.imageshack.us/img138/1665/img7024w.th.jpg" alt="http://img138.imageshack.us/img138/1665/img7024w.th.jpg" style="border:0" /></a>
<a href="http://img194.imageshack.us/i/img7025a.jpg/" target="_blank"><img src="http://img194.imageshack.us/img194/9608/img7025a.th.jpg" alt="http://img194.imageshack.us/img194/9608/img7025a.th.jpg" style="border:0" /></a>
<a href="http://img638.imageshack.us/i/img7026t.jpg/" target="_blank"><img src="http://img638.imageshack.us/img638/9210/img7026t.th.jpg" alt="http://img638.imageshack.us/img638/9210/img7026t.th.jpg" style="border:0" /></a>

Link to the page includes comments about the sizes of the shells: <a href="http://profile.imageshack.us/user/jtroop/" target="_blank"><!-- m --><a class="postlink" href="http://profile.imageshack.us/user/jtroop/">http://profile.imageshack.us/user/jtroop/</a><!-- m --></a>