THE CLIMAX FOREST AND ITS PREDECESSOR 215 



Its shell is narrowly umbilicate. P. monodon is not hairy, the lip is 

 not notched, and it is widely umbilicate. The following are much 



a 



t 



FIG. 284. Various species of Polygyra, common land snails, life size: 

 a, Polygyra al.bolabris, the white-lipped snail (note covered umbilicus) ; b, P. hirsute, 

 the hairy snail (note notch in lip); c, P. mullilineaia, the many-banded snail; 

 d, P. palliate; e, P. pennsylvanica; f, P. profunda (note wide open umbilicus); 

 g, P. thyroldes; h, P. tridentete, the three-toothed snail. 



