152 Chlorophycese 



Series III. Chroolepoidales. 

 Family : Chroolepidacese. 



Series IV. Siphonales (sensu Oltmanns). 



B. Pleotrichales. 



Series I. (Edogoniales. 



Family : CEdogoniaceae. 



C. Atrichales. 



Series I. Conjugates. 



Families : Desmidiaceae ; Zygnemaceae. 



It will be noticed that the Heterokontae are missing from the above scheme, Chodat 

 having placed them [along with the Peridinieae, Bacillarieae, and the Euglenaceee] within 

 the Pheeophycete ! 



The creation of the three new names Meiotrichales, Pleotrichales and Atrichales 

 seems scarcely necessary, as they are merely equivalent to the older and better names 

 of the Isokontae, Stephanokontse and Akontae. Moreover, they have the great disadvantage 

 that the termination ' -trichales ' (and also ' -trichaceae ') in the group-names of Algee has 

 so far been exclusively used in reference to hair-like branches and filaments, and not to cilia. 

 It is doubtful if there is any real justification for the inclusion of the ' Pleurococcaceae,' 

 Ulotrichaceae and Chfttophoraceae within the one series of the ' Pleurococcales,' apart 

 from the extraordinary use of this group-name to include filamentous and branched Green 

 Algae. The Chaetophoraceae are merely the branched forms of the Ulotrichaceae, and the 

 evolutionary series of the latter through such forms as Geminella, Stichococcus, etc., is 

 almost perfect, the most probable origin of the lower types being from some of the 

 Tetrasporine Protococcales with thin cell-walls and simple parietal chloroplasts. Chodat 

 also includes the Ulvaceas in his ' Pleurococcales,' without giving any reasons for such a 

 step, and he places Bulbochsete (surely by an accident) in the Coleochaetaceae. 



[The foregoing classification has been very recently modified by Chodat ('13), the 

 principal alterations being in the 'Meiotrichales,' in which 'series I Protococcales' is 

 changed to 'series I Cystosporese ' and 'series II Pleurococcales' is changed to 'series II 

 Parietales.'] 



V. WILLE ('09) recognizes neither the Heterokontae nor the Stephanokontae, and his 

 proposed new classification is in some ways a retrogression. He still maintains the 

 Conjugatae as a group equivalent to the remainder of the Green Algae ('Chlorophyceae'), 

 and the various members of the Heterokontae are scattered with little regard to their 

 affinities among the families of the Protococcales and the Chaetophorales. It is difficult to 

 see any reason for the inclusion of both Tribonema and Microspora in the Ulotrichacese. 

 Following West ('04) and Oltmanns ('04), Aphanoch&te is regarded as the type of a separate 

 family. Wille's ' Pleurococcaceae ' is a very mixed assemblage, including some members of 

 the Palmellaceae and Heterokontae, and one lichen (Botrydina). Elakatothrix is also 

 included in the Pleurococcaceae, although this genus is so closely related to Ankistrodesmus 

 as to be hardly separable from it. His Chaetophorales is enlarged in scope and somewhat 

 unwieldy, and is certainly not equivalent to the ' Confervales.' His system is briefly as 

 follows : 



Chlorophyceae. 



Class Protococcales. 



Families : Volvocaceae ; Tetrasporaceae ; Botryococcaceae ; Pleurococcacete ; 

 Protococcaceaa ; Ophiocytiaceae ; Hydrogastracese ; Oocystaceae ; Hydro- 

 dictyaceae ; Ccelastraceae. 



