The Pearly Mussels of Pennsylvania Author:Al Spoo Each of the sixty-six species of freshwater mussels from Pennsylvania waters (including extant and extirpated species) is described and illustrated by the author. Al Spoo provides multiple views for each species on full-color plates, and offers keys for distinguishing them. Freshwater mussels are a rapidly disappearing resource, and this book of... more »fers a detailed look at these fascinating natural treasures.« less