Need help to identify Costa rica Pacific shell....beginner issue

[paul monfils]

Hello! Welcome aboard!  I'll see what I can do with these, but for the future, two recommendations - first, take your pictures straight-on, not at various angles.  This makes it more difficult to determine the actual shape of the shell.  Lay a bivalve flat on the table, and shoot it from directly above, looking straight down.  With gastropods, position the shell on a lump of modeling clay so that you get a straight-on shot of the dorsal view and the ventral view, again shooting straight down.  Secondly, mention the size of each specimen you post.  Sometimes two species are similar, but one of them doesn't exceed an inch in length and the other may be much larger.

The book you need is Sea Shells of Tropical West America by Myra Keen.  Unfortunately it is out of print, and copies when available are pretty expensive.

<!-- m --><a class="postlink" href="http://www.alibris.com/booksearch?qisbn=9780804707367&qsort=p&cm_mmc=shopcompare-_-pricegrabber-_-books-_-used">http://www.alibris.com/booksearch?qisbn ... oks-_-used</a><!-- m -->

There are copies of her earlier book (same title, I believe) on Amazon.com pretty cheap.  The book is more than 50 years old and smaller than the one listed above, but you still might find it useful.

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OK, on to the shells:

392/393 - Cymatium (Septa) vestitum
394/395 - Astraea buschii
402 - Tellina sp., best guess Tellina eburnea
411/412 - Cardita affinis
435 - May be Pitar roseus (the angle makes it hard to tell).  Could also be Pitar lupanaria, with the spines worn off.
440/442 - Too worn to be certain, best guess Crepipatella dorsata
443 - Donax sp., best guess Donax navicula
447/448 - Donax sp., best guess Donax peruvianus
449/445 - This a land snail, probably a species of Lampadion
454/455 - Trivia radians
460 - Olivella sp., best guess Olivella volutella (again, poor angle, and ventral view would help)
464 - Terebra robusta

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