58 / MR. A. W. BENNETT ON THE 
Various families of Phæosporeæ exhibit reduction or degrada- 
tion of the vegetative structure. Considerable obscurity rests 
on the position of the small group named by Rostafinski Synge- 
netice ; but I am disposed to agree with Hansgirg * in regarding 
it as having descended by retrogression from the Phæosporeæ. 
The two genera of which it is composed resemble one another in 
but few points except the possession of a brown endochrome, and 
have probably but slight affinity with one another. Hydrurus 
is a unicellular freshwater organism in which the reproductive 
bodies are reduced to non-ciliated masses of brown protoplasm 
wbich germinate directly without impregnation; in Chromo- 
phyton, which is endophytic in Sphagnum, the vegetative struc- 
ture is almost entirely suppressed, and the reproductive bodies 
are uniciliated masses of protoplasm of two kinds, but without any 
observed process of conjugation. Heckel and Chareyre t regard 
the Diatomacew, Syngenetice, and Phæosporeæ as successive 
members of an ascending series. 
The step from the Dictyotez to the Fucace® is an easy one. 
In the highest type of brown seaweeds, such as Fucus or Dur- 
villea, with their typical heterogamous or **oogamous"' repro- 
duction, consisting of the impregnation of a comparatively large 
oosphere by a number of minute antherozoids, we have the climax 
. of this line of evolution. 
The third line of descent from the isogamous Confervoides is 
a much more direct one, viz. to the Confervoides heterogamz, 
consisting of the three families Spheropleacee, (Edogoniacec, and 
Coleochetacee. In the first of these, which comprises only a single 
species, we have a distinct differentiation of the male and female 
reproductive elements, the latter having now become permanently 
quiescent, but still a strong reminiscence of the Confervace® in 
the unbranched filament and the multinucleated cells. The 
Œdogoniaceæ exhibit a distinct advance in vegetative structure, 
and still more in the cells which contain the male and female 
reproductive bodies being, for the first time in this series, differ- 
entiated into antherids and oogones respectively. In the purely 
sexual system of classification these two families are placed 
among the Oophycesm, while the most highly developed of the 
three, the Coleochætaceæ, commences the series of Carpophycee. 
* ‘ Prodromus der Algenflora von Böhmen,’ 
t ‘Journal de Micrographie, 1885. 
