FOSSIL CEYPTOGAMS 249 



traced progressing from cell to cell. The Coal Measure 

 petrifactions yield no trace of Mosses, but there are 

 impressions of these plants in strata of later age. Re- 

 mains of Liverworts are scanty, and such as have been 

 found, the most common being called Marchantites, 

 throw no light on evolutionary problems. 



32 



