90 



CJdorophycece 



also resembles the Trentepohliacese but differs in the aquatic 

 habit, smaller size, and in the nature of the chloroplasts. 



Chodat includes the plants of this family in the Pleurococcacese. 

 but they have unquestionably reached a higher stage of develop- 

 ment than Pleurococcus or Trochiscia. 



Genus Microthamnion Nag., 1849 ; Kirchn., 1878. The plants 

 of this genus are at first fixed but afterwards they often float 



Fig. 32. A D, Microthamnion Kiitzingianum Niig. A C, young forms from 

 Richmond Park, Surrey (xoOO). D, portion of adult form from Horton-in- 

 Ribblesdale, W. Yorks. (x350). E, M. strictissimum Rabenh., from Blubber- 

 houses, \V. Yorks. ( x 500). 



freely. The filaments are branched and the branches may be short 

 or long. The cells are cylindrical, 3 7 times longer than their 

 diameter, and the terminal cells of the branches are obtuse or 



