212 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
study. It was completed at the University of Indiana in connection 
with my duties as instructor. 
It is a pleasure and a duty as well, to express my thanks to Pro¬ 
fessor Thaxter who has given assistance in many ways and whose 
interest in the investigation has been shown throughout its progress. 
In this connection, I also wish to thank Prof. David M. Mottier, of 
the University of Indiana, who has made occasional suggestions and 
has enabled me to arrange my work at the University in such a 
way as to interfere least with the progress of this research. 
History. 
The history of the genus Araiospora is extremely brief. This is 
probably due to two causes: first, it is, so far as known, quite rare ; 
second, it is an inconspicuous fungus and easily escapes observation. 
The first reference to a member of the genus is made by Cornu (’71) 
when the genus Rhipidium was established with three species: R. 
interruptum , R. elongatum , and R. spinosum. A limited number 
of the zoosporangia of the last named species, all of which are sub- 
umbellately borne, are furnished with spines that are directed 
upward and downward. Nothing more was seen or known of this 
species or even of the genus until the appearance of Professor 
Thaxter’s paper. In this paper he figures and describes in detail a 
new species of Rhipidium, R. americanum , and another closely 
resembling it but generically different, for which he creates the 
genus Araiospora. The latter, Thaxter suggests, is probably gener¬ 
ically identical with the Rhipidium spinosum of Cornu mentioned 
above. The American form, however, differs from Cornu’s species 
in certain points of specific importance ; for example, instead of 
having the spines of the zoosporangia turned upward and down¬ 
ward, they extend out radially and are scattered over the entire 
surface of the zoosporangium. Finally, Minden (: 02 ) has described 
a third species of Araiospora. So far as known, therefore, the genus 
Araiospora probably consists of but three species, A. spinosa 
(Cornu) Thaxter, A. pulchra Thaxter, and the new Araiospora of 
Minden, and up to, the present time, has been observed by no other 
writers. 
