Classification 151 



There is little, if any, justification for the inclusion of the Tetrasporaceae (especially as 

 constituted by Oltmanns) in the ' Volvocales,' and it is very doubtful if the Volvocinese 

 have sufficient claims to be removed from the Protococcales and elevated to a group of 

 equal rank (the ' Volvocales '). The ' Halosphaeraceae,' established to include Halosphxra 

 and EremosphseroL) is purely artificial, as everything known concerning these Algae indicates 

 that they are in no way nearly related. There seems little need for the ' Scenedesmaceae,' 

 which if Dictyospkaerium be excluded, is equivalent to the Autosporaceae (the ' Protococ- 

 caceso Autosporese ' of Chodat) and also with very slight differences is synonymous with 

 Blackmail & Tansley's ' Selenastraceae.' Oltmanns' inclusion of the CEdogoniaceee within 

 the Ulotrichales is in striking contrast to his whole-hearted acceptance of the Heterokontse 

 as a primary group ; and his use of the name ' Protococcacess ' is not altogether in 

 agreement with its original meaning, but is in part synonymous with the modern 

 conception of the Chlorochytriacese ( = Endosphaeraceae). The Vaucheriacese is retained 

 within the Siphonales. In outline the arrangement is as follows : 



ffeterokontas. 



Families : Chloromonadacese ; Confervacese ; Botrydiaceae ; Chlorotheciacese. 

 Acoiitee (Zygophyceae). 



a. Conjugatae. 



Families : Mesotaeniaceae ; Zygnemaceae ; Desmidiaceau. 



b. Bacillariacea3. 

 C/tlorophi/cec. 



a. Volvocales. 



Families : Polyblepharidaceae ; Chlorodendracese ; Chlamydomonadacess ; 

 Phacotaceae ; Volvocaceae ; Tetrasporacea. 1 . 



b. Protococcales. 



Families : Protococcacese ; Protosiphonaceae ; Halosphoeracese ; Scenedes- 

 maceae ; Hydrodictyaceee. 



c. Ulotrichales. 



Families : Ulotrichaceae ; Ulvacese ; Prasiolaceae ; Cylindrocapsacese ; CEdo- 

 goniaceae ; Chaetophoracese ; Aphanocheetaceae ; Coleochajtaceae ; Chroole- 

 pidacese. 



d. Siphonocladiales. 



Families : Cladophoraceae ; Siphonocladiacese ; Valoniaceae ; Dasycladiaceas ; 

 Sphseropleacese. 



e. Siphonales. 



Families ; Codiaceie ; Bryopsidacese ; Derbesiace&e ; Caulerpaceae ; Vaucheri- 

 aceae. 



IV. CHODAT has recently ('09) proposed a 'natural system' of classification for the 

 Green Alga?, but in many respects the proposed system is very confusing. It is briefly as 

 follows : 



A. Meiotrichales. 



Series I. Protococcales. 



Families : Volvocaceae ; Palmellaceaj ; Protococcaceae (Prot. Zoosporees ; 



Prot. autosporees ; Prot. hemizoosporees). 

 Series II. Pleurococcales. 



Families : Ulotrichaceae ; Ulvaceae ; Pleurococcacea 1 ; Prasiolaceae ; Chaeto- 

 phoraceaj ; Coleochcetacese. 



