328 The Botanical Gazette. [June, 
duce oospores, and their zoosporangia are also subject to the 
greatest amount of variation both in form and in size 
Like Blastocladia, with which it is very often associated, it 
usually grows under rather unfavorable conditions, being sur- 
rounded by a mass of bacteria and other foreign organisms 
and under these circumstances it is apt to assume abnormal 
and irregular forms. Under such conditions the discharge 
of the zoospores, which isin any case a very rapid process, is 
usually not accomplished in the characteristic fashion above 
described, through the rupture of the inner membrane at the 
moment of dehiscence. The filaments are far more com- 
monly unsegmented, and each sympodial branch is as a rule 
distinctly clavate in form, tapering towards its point of origin 
just below the sporangium. The oogonia in all observed in- 
stances have been terminal and as a rule are formed after the 
production of zoospores has begun to cease. The species is 
more closely allied to R. continuum than to R. interruptum and 
may prove identical with it when the former has been intel- 
ligibly described. The dichotomous branching of its basal 
cell, and its androgynous character as well as its very short 
antheridial filaments serve to distinguish it in the absence of 
further knowledge of the European form. 
Araiospora pulchra, nov. sp.—Plate XXIII, figs. 20-25: 
Basal cell variably developed, usually large, sub-cylindrical, 
the ramiferous extremity sub-conical, bearing often numerous 
(forty or less) acropleurogenous branches in a more OF is 
distinctly umbellate fashion and separated from it by the usu 
constrictions. The branches composed of more or less cylin- 
drical segments and re eatedly umbellately branched, the 
segments sub-cylindrical becoming more slender and usually 
smooth; or broadly oval to piriform and furnished with large 
Spines radiating in all directions but sometimes short v 
stout and confined to the distal extremity. Oogonla pie 
like the sporangia, the constricted portion which sepatee 
them from the segment very short. Oospore spherical, yl 
thick wall colorless, surrounded by a single layer of mor a 
less hexagonal peripheral cells derived from the periplas™ 
Basal cell 1 to 1, 5™ long by 50-25. Filaments 2750-27 a8 
ong. Sporangia 120x 30-1 75X35paverage 125 X 30H: long 
Spinose forms about 45-60 x 48-70p the spines 10-350 te 
