88 



defined volutions : aperture roundish-oval : the 

 peritreme thin, simple and a little reflected at the 

 pillar so as to form a slight umbilicus. In old and 

 full-grown shells may be observed a slight fold 

 or tooth about the middle of the pillar, but which 

 is seldom to be met with. 



On the trunks of trees, under the bark, and imbed- 

 ded in the Lichen which grows on old apple-trees ; 

 also in the fissures of rocks. 



