Division II. AKONT^E 



The name ' Akontas ' was first given to this group of the Chlorophyceas by 

 Blackman & Tansley ('02) and by them regarded as equivalent to the older 

 name ' Conjugatse.' The name is here retained for one of the four primary 

 divisions of the Chlorophycese, and is applied to that group of the Green A Igx 

 which is characterized by the complete absence of ciliated reproductive cells. 

 Thus, neither zoogonidia nor ciliated gametes occur in any member of the 

 group. 



In 1904 Oltmanns extended the scope of the Akontas to include both the 

 Conjugatse and the Bacillariea?, but, since there is no evidence of any close 

 phylogenetic relationship between these two groups, this arrangement cannot 

 be upheld. The analogy between the structure of the cell-wall in Diatoms 

 and Desmids, as instituted by Oltmanns, does not stand the test of enquiry 

 (vide p. 119). 



The only Green Algae at present known which can rightly be placed in 

 the Akontae are those belonging to the Conjugatse and under this heading 

 the general characters of the group can be best discussed. 



The Conjugate is here placed as an order of the Akontae, since there may possibly be 

 other Algae in existence which should be included in this division, and it is also a con- 

 venient means of retaining the old name. 



Order 1. CONJUGATE. 



The order Conjugatse is one of the best defined and most natural groups 

 of the Green Algse, embracing only two families. In the ZygnemaceaB the 

 thallus consists of unbranched filaments of cylindrical cells, but in the 

 Desmidiaceae the plants are unicellular and generally exhibit a remarkable 

 specialization of form. Some genera of the Desmidiacese have become 

 secondarily filamentous, but the filaments are mostly rather fragile and easily 

 become dissociated into their individual cells. 



