1896. ] Aquatic Fungi. 319 
ial filament is spirally twisted below the antheridium, which 
applies itself to the apex of the oogonium by means of a ter- 
minal beak-like process. Whether the filaments are umbel- 
lately or otherwise branched is not mentioned. 
R. spinosum, the fourth and last of the species described, 
is still more imperfectly known; but may be distinguished 
from the others by the fact that its sporangia are furnished 
with stout spines directed upwards and downwards, and are 
borne sub-umbellately at or near (?) the tips of the segments. 
Ifone compares this fragmentary information, which, al- 
though it is perhaps sufficient to distinguish these four spe- 
ties from one another, is quite inadequate to afford a means 
of separating them from other allied forms, it becomes ap- 
parent that, although the two first, together with the Amer- 
(Can species subsequently described, are undoubtedly con- 
generic, the others are by no means certainly so. The 
characters of R. elongatum in particular, so far as we are in- 
formed concerning them, when compared with those of the 
Species of Sapromyces, indicate a generic identity which can 
hardly be-doubted. On the other hand the characters of R. 
‘Pinosum suggest a similar identity with the generic type 
described below as Araiospora. To make these points more 
"at @ brief review of the chief characters of the three genera 
Nst mentioned will be necessary. ee 
he genus Rhipidium, if we limit it as above indicated to 
the three species R. interruptum, R. continuum and R. Amer- 
anum, is characterized by a differentiation, more extreme 
setts to which it gives rise. This basal cell is distinctly 
4. seneris, and although it may be variously modified from 
> fact that it is often more or less regularly branched - 
; d, is utterly different in character from the segments 0 
€ bra 
tie? thickened and it is, as a rule, very abruptly expanded 
by Num 
“utface of the expanded portion, from which they al dae 
by: a constriction, are produced the filaments; an¢ on 
| 
“a are borne the reproductive organs. These peer reine be 
tial members of the Leptomitacee, are characteriz 
g 
: : rked 
Mentation which, as we have seen, 1s very well ma 
