An investigation into the functional and symbolic uses of shells during the pre-conquest era in the Occidente region of Mexico. The author first provides a classification list of known examples, then proceeds to interpret those examples, giving information on provenance, find context, date and function. He concludes that the presence of shell artefacts in the region is the result of a deliberate selection of that material - since the species represented were of relatively little food value - for functional/symbolic purposes.