Dear Tom,
 
Amathina tricarinata is a member of the family Amathinidae, superfamily
Pyramidelloidea (this latter also includes pyram snails, turbonillas, and
odostomes). Its shell vaguely resembles those of capsnails in the family
Capulidae, and was until recently included in this latter family. It is not
a limpet. The most striking conchological feature in A. tricarinata is the
presence of the three strong spiral keels mentioned in the species name.
 
Best,
__________________________________________________________________________
Jose H. Leal, Ph.D.
Director, The Bailey-Matthews Shell Museum
Editor-in-chief, THE NAUTILUS
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(941) 395-2233; fax (941) 395-6706
 
"But fit the facts together in any other way and you get more nonsense
instead of less." -- Travis McGee