Classification 151 



There is little, if any, justification for the inclusion of the Tetrasporacese (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 Halosphsera 

 and Eremosphxra, 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 Dictyosph&rium be excluded, is equivalent to the Autosporaceae (the ' Protococ- 

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

 Blackman & Tansley's ' Selenastraceae.' Oltmanns' inclusion of the CEdogoniaceae within 

 the Ulotrichales is in striking contrast to his whole-hearjbed acceptance of the Heterokontee 

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

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

 conception of the Chlorochytriaceae ( = Endosphaeraceae). The Vaucheriaceae is retained 

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



Heterokontx. 



Families : Chloromonadacese ; Confervaceae ; Botrydiaceae ; Chlorotheciaceae. 

 Awmtffi (Zygophyceae). 



a. Conjugate. 



Families : Mesotaeniaceae ; Zygnemacese ; Desnaidiaceae. 



b. Bacillariaceie. 

 Clt lorophyceiv. 



a. Volvocales. 



Families : Polyblepharidaceae ; Chlorodendraceae ; Chlamydomonadaceae ; 

 Phacotaceae ; Volvocaceae ; Tetrasporaceaj. 



b. Protococcales. 



Families : Protococcaceae ; Protosiphonaceae ; Halosphaeraceaa ; Scenedes- 

 maceae ; Hydrodictyaceae. 



c. Ulotrichales. 



Families : Ulotrichaceae ; Ulvaceae ; Prasiolaceae ; Cylindrocapsaceae ; CEdo- 

 goniaceae ; Chaetophoraceae ; Aphanochaetaceae ; Coleochaetaceae ; Chroole- 

 pidaceae. 



d. Siphonocladiales. 



Families : Cladophoraceae ; Siphonocladiaceae ; Valoniaceae ; DasycladiaceaB ; 

 Sphaeropleaceae. 



e. Siphonales. 



Families ; Codiacete ; Bryopsidaceae ; Derbesiaceae ; Caulerpaceae ; Vaucheri- 

 aceae. 



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

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

 follows : 



A. Meiotrichales. 



Series I. Protococcales. 



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



Prot. autospore"es ; Prot. hemizoosporees). 

 Series II. Pleurococcales. 



Families : Ulotrichaceae ; Ulvaceae ; Pleurococcacerc ; Prasiolacea? ; Cluoto- 

 phoraceae ; Coleochaetaceae. 



