322 BOTANICAL GAZETTE | NOVEMBER 
zoospore formation in Eremosphaera were repeated with Excen- 
trosphaera, but without success. 
The Eremosphaera material found on Naushon has never 
shown Excentrosphaera, nor has the Ridge hill material devel- 
oped it after the original lot was collected. Excentrosphaera 
has been found in stagnant ponds near Norwich, Vt., which 
contained, in addition, large amounts of Nitella, Spirogyra, 
Oedogonium, and related forms. A shallow pool, almost filled 
with Hydrodictyon, not far from Boston, has also furnished 
Excentrosphaera in considerable quantities. Neither of these lat- 
ter localities have ever shown Eremosphaera, although repeated 
search has been made for it. Unless we are to adopt Borzi’s 
‘‘stadii anamorphici”’ for all the algae, it does not seem possible 
that this plant has any genetic connection with any other form. 
The external resemblance to Centrosphaera, which led Chodat 
to give that name to it as a supposed stage of Eremosphaera, is 
certainly striking, but the decided difference in habitat, together 
with the absence of motile spores and the difference in develop- 
ment, would seem to be sufficient to separate it from that genus. 
The affinities of Excentrosphaera, so far as known, must be with 
the Protococcaceae of Wille. 
Excentrosphaera, nov. gen. — Plant consisting of a single 
cell, in mature condition varying in outline from spherical and 
elliptical to irregular and excentric forms. Chromatophores 
large, angular, usually radiately arranged, closely lining the wall. 
Pyrenoids minute, numerous in each-chromatophore. Multipli- 
cation by means of non-motile spores (aplanospores), which 
escape by the dissolution of a part of the cell wall. Reaction 
to all external stimuli negative. 
E. viridis, nov. sp.— Plate XII, figs. 21-27. Characters of 
the genus. Plants of bright green color; size of mature cells 
22-55. Spores 2-34. Growing with Eremosphaera, Geneva (?); 
with Eremosphaera, Micrasterias, Zygnema, etc., Ridge hill, 
Mass., the year around; in swamps with Nitella and various 
algae, Norwich, Vt., September—November; with Hydrodictyon 
in shallow pool, in vicinity of Boston, June-August. 
