200 WET FOREST COMMUNITIES 
Subterranean-ground stratum: The nymphs of the seventeen-year 
cicada and the two-year cicada together with earthworms are always 
numerous. The latter comes out on the ground under a log and ascends 
under the bark of dead trees during wet weather. 
On the ground one finds slugs (Agriolimax campestris). Under 
leaves, logs, and bark are snails (Circinaria concava, Polygyra profunda, 
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REPRESENTATIVES OF THE FLOOD-PLAIN ForEST ANIMAL COMMUNITIES 
Fic. 151.—A caterpillar (Symmerista albifrons) on the leaf of the soft maple; 
natural size. 
Fic. 152.—The common land sowbug (Porcellio rathkei); twice natural size. 
Fic. 153.—The scorpion fly (Panorpa venosa); much enlarged. 
Fic. 154.—A sphinx caterpillar from Virginia creeper; natural size. 
Fic. 155.—The unicorn larva from dogwood; enlarged. 
Pyramidula alternata, and Polygyra clausa, and rarely thyroides). Land 
sowbugs are common (Fig. 152). Of the centipedes we note the long 
ground form (Geophilus sp.) and sometimes the large millipede (Spiro- 
