Boy Scouts Handbook / The First Edition, 1911

by Boy Scouts of America

Fig. 4 Orb-Shell (Planorbis trivolvis)

Fig. 5 Black Mussel (Mytilus)

Fig. 6 Bubble snail (Physa heterostropha)

The squids, cuttle-fishes, octopus, and their allies are also mollusks, but not so accessible to the ordinary collector, and can only be kept in spirits.

Books which may help the collector to identify the shells he may find are:

For the land and fresh-water shells:

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"Mollusks of the Chicago Area" and "The Lymnaeidae of North America." By F. C. Baker. Published by the Chicago Academy of Sciences.