412 THE AMERICAN NATURALIST. [Vor. XXXV. 
isa natural one. According to Blackman, the green alge may be 
considered to originate from two flagellate forms, Chlamydomonas 
and Chlorameeba. From the first type three divergent lines of ascent 
go off: one leading to Volvox, including the type of motile cell 
aggregations, another ending in the so-called unicellular Siphonez. 
The third, by far the largest and most important, is called the Tetra- 
sporine type, including forms of non-motile cell aggregations, the main 
stem of which leads through the simple filamentous forms to the 
branched Coleochzte, and finally, it is to be supposed, to the higher 
plants. The Ulvas are properly placed as a specially developed 
side branch. The always perplexing Conjugatez are indicated as 
forming a possible fourth line of ascent from the Chlamydomonas 
type. 
The green alge which arise from the second flagellate form, 
Chlorameeba, include Ophiocytium, Conferva, and finally the Botryd- 
ium forms. It is considered that the gametes of these have in 
reality two cilia, not one, as previously believed. They are included 
under the head of the Confervales (Borzi), a title not coincident with 
that used by other authors, and, with their flagellate ancestors, form 
a group called the Heterokontze. ; 
The Phzophycesz are derived from a brown flagellate, Chromulina, 
allied to the green Chloramceba. This is widely different from the 
older view, which recognized the simplest Ectocarpus type as the 
most primitive brown form.  Phzocystis, a form on the border line 
between alge and flagellate, is taken as the next step in the direc- 
tion of plants, and is connected with the recently described un- 
doubted algæ forms, Phzeothamnion and Pleurocladia, and thence with 
the Ectocarpus type. The Piatones constitute a side branch from 
Chromulina. 
The red seaweeds, it is suggested, find their origin in a flagellate 
form (Rhodomonas), which is said to possess a chromatophore of true 
Floridian red color. 
However much one may or may not agree with the conclusions, 
the paper is a suggestive one and a valuable review of the status of 
the subject. The changes suggested regarding the Chlorophyceous 
algæ seem certainly to be in the right direction, except that the con- 
nection of the Botrydium forms and Conferva type is not very appa" 
ent. As to the brown algz the identity of the flagellate ancestor does 
not seem absolutely certain and convincing. A flagellate ancestor for 
the red seaweeds is a matter of such doubt that, as the author say® 
it is no more than a suggestion which he makes. H. M. R. 
