320 BOTANICAL GAZETTE [NOVEMBER 
ascribed to it by Chodat (rt) and Wille (7). Chodat, as the 
result of his study of Eremosphaera, came to the conclusion that 
it had evident affinities with the Volvocaceae, and if all the stages 
described by him are really passed through by this plant, it 
would seem as though some such disposition would have to be 
made of it. On the other hand, the negative results of my cul- 
tures and observations would seem to throw some doubt upon 
its supposed polymorphism, particularly with regard to a motile 
stage. It seems, therefore, that for the present at least, Ere- 
mosphaera should be classed with the group of green algae pos- 
sessing no zoospores, namely the Protococcoideae. 
Excentrosphaera, nov. gen. 
There still remains to be discussed the form described by 
Chodat as the ‘“‘Centrosphaera” stage. This form was present 
in small quantities in the first material collected at Ridge hill, 
and was immediately separated from the Eremosphaera cells and 
cultivated. The growth was luxurious in fluid nutrient media, 
and satisfactory, if not so abundant, on agar. In addition to these 
pure cultures, a number of dishes containing water from the pool 
which supplied the original material were kept in the laboratory, 
and in the course of a few months became filled with a large 
number of these plants. The conditions for growth under these 
various circumstances seemed favorable and normal, but there 
was at no time any evidence of the slightest connection with the 
developmental history of Eremosphaera. After having had this 
form under cultivation for about three years, and having seen it 
pass through its life cycle over and over without assuming 4 
stage which in any way resembled those of Eremosphaera, I am 
obliged to conclude that it is an independent genus. Since it 
does not seem to have been described elsewhere, the name 
Excentrosphaera viridis has been given to this alga. 
Excentrosphaera, in its mature condition, may assume an out- 
line varying from that of a perfect circle, through all gradations 
to an ellipse, as well as occasional excentric and indefinite shapes. 
The general resemblance to the forms assumed by germinating 
