*43 
The British Freshwater Algce. 
however, that there is no direct evidence in support of the view that 
the CEdogoniales and Conjugatae are phylogenetically independent 
of the rest of the Chlorophyceae.” And he goes on to insist that 
his long intimate acquaintance with the Conjugate has tended to 
shew that they at least have not had a direct origin from Flagellate 
ancestors. There is something to be said for Mr. West’s contention 
here. It is implied though not specifically stated in the Introduction 
to the “ Revision” that the Conjugate had an independent Flagellate 
origin, but the authors of that work scarcely intended to emphasise 
the point. Their view is better expressed in the remark that “we 
have not at present sufficient evidence, in the complete absence of 
zoospores, to settle the phylogenetic origin of the group ” (p. 2 of 
Reprint), though they elsewhere state that “ it may possibly have 
been derived from a primitive motile form” and call attention to 
the analogy with Clilainydomonas Braunii in the peculiar mode of 
conjugation (p. 45). It nevertheless seemed to them desirable to 
separate the Conjugatae from the other green algae on account of 
the very striking aud sharply marked characters presented by the 
group, both in cell-structure and in the mode of reproduction. 
There is certainly no good evidence that the Conjugatae have arisen 
from any existing Isokontan filamentous forms. We will deal with 
Mr. West's “proof” that they arose from filamentous ancestors 
presently. It is perfectly true also that there is no direct evidence 
for the separate origin of CEdogoniales from Flagellata with an anterior 
crown of cilia. The case for their separation as “ Stephanokontae” 
is an a priori case, and rests on the great constancy of the 
zoospore-characters in the other series (including Phaeophyceae) and 
the absence of intermediate forms between the bi-flagellate or 
quadri-flagellate type of motile cell and the multi-flagellate type. 
Once the great importance of the motile cell as a taxonomic basis 
is admitted, this indirect evidence acquires, in our opinion, very 
considerable weight and appears to justify the application of the 
Luther-Bohlin conception throughout the Green Algae. It must, 
however, be admitted that such an extension of the principle does 
not at present rest on the same solid ground as in the case of the 
Heterokontae and Phaeophyceae. 
We notice that in Mr. West’s phylogenetic table (p. 30) the 
dotted line of origin of the G2dogoniales does not connect with any 
existing group, but arises freely and independently on the level of 
the Protococcoideae. We should be inclined to carry the line down 
a little further, into the region of the Flagellata. That is all the 
difference. 
