228 THALLOPHYTA. [CH. VII 



by other writers from several other districts. Beds of calcareous 

 marl are occasionally seen as whitish streaks in the peat 

 of the Fenland^; these often consist in great part of Charas. 

 A season's growth of Chara in a shallow lake or mere in the 

 Fens may appear as a white line in a section of peaty and other 

 material which has been formed on the site of old pools or 

 lakes. 



The recognition of specific characters in the isolated Chara 

 'fruits' usually met with in a fossil state is exceedingly un- 

 satisfactory ; the features usually relied on in the living species 

 are not preserved, and great care should be taken in the separa- 

 tion of the various forms. 



1 Skertchly (77) p. 60. 



