CHLOROPHYCE^E 



143 



FIG. 41. a. Halimeda monilis half natural size ; b, the same in longitudinal 

 section highly magnified. 



Callipsygma is a genus of which only an imperfect 

 description has been published. It appears to be 

 related to Avrainvillca and Udotea. 



A fossil Alga of Devonian Age, Nematophycus, has 



