BEECH ASSOCIATION 243 



a) Subterranean-ground stratum. — Earthworms continue; an occa- 

 sional groundhog has been seen, though they are probably much less 

 common here than in the preceding stages. The stratum appears less 

 closely inhabited than the preceding. Under leaves are found scattered 

 snails, centipedes, etc. The yellow-margined millipede (Fontaria cor- 

 rugate) is most common. There is an occasional Centhophilus. We 

 have found no other Orthoptera in beech woods proper, though 

 Hancock records several (40, p. 422). Animals are more abundant 

 under logs than under leaves. Here we find the large slug (Philomycus 

 carolinensis) and several species of snails which, though characteristic, 



Figs. 234-240. — Some beech woods snails: Ground stratum; 234, Pyramidula 

 perspectiva; 235, Polygyra inflecta; 236, Polygyra palliata; 237, Polygyra frandulenta; 

 238, Polygyra oppressa; 239, Pyramidula solitaria, adult; 240, Polygyra albolabris. 



are not abundant. These snails are Polygyra inflecta (Fig. 235), 

 oppressa (Fig. 2$$),fraudulenta (Fig. 237), palliata (Fig. 236), albolabris 

 (Fig. 240), Pyramidula solitaria (Fig. 239), alternaia, and perspectiva 

 (Fig. 234), and Zonitoides arboreus. These species of Polygyra are 

 distinguishable by the presence of characteristic "teeth" in the 

 entrance of the shells. The large spider (Dolomedes tenebrosus) and 

 millipede (Spirobolus marginatus) occur. Crane-fly larvae, ground 

 beetles (Plerostichus cdoxus), a centipede (Geophilus rubens) i the wood- 

 frog (Rana sylvatica) (Fig. 241) (139), and the red-backed salamander 

 (Plethodon cinereus) (152) (Fig. 242) are common and characteristic. 



