404 BOTANICAL GAZETTE [DECEMBER 
was sand, but this was covered by a soil mixture of half leaf mold 
and half muck, covering lake sand. As a matter of fact, some of 
it was nearly pure mycelial threads. Other parts were as hard as 
dry muck itself. The prothallia found here grew for the most part 
in the intensely moldy soil. Some were found at the border 
between the humus layer and the sand lying beneath it. From 
this it will be seen that one cannot name a type of soil as a criterion. 
If it is desirable to indicate the type of place to look for Lycopo- 
dium prothallia, I should say that one should look in neither the 
dry nor the wet places. For my own part I search in those spots 
a little less moist than the habitat of the adults. In the case of 
L. obscurum and L. clavatum, very often the reverse is true, but 
just as one cannot give a precise type of soil and moisture content 
for the sporophytes, so he cannot for the gametophytes. 
Sporelings were found in a variety of other places near Marquette 
and Munising. The prothallia of ZL. obscurum probably grow 
abundantly wherever the sporophyte has been known to exist for 
a long time and in considerable quantity. Two prothallia and one 
sporeling were found in July 1922, near Rhinelander, Wisconsin. 
A sporeling and an old prothallium of L. complanatum were found 
in June 1922, near Pembine, Wisconsin. 
DESCRIPTION OF PROTHALLIA 
The prothallia are of the L. annotinum type and not of the L. 
complanatum type suggested in my first paper (4). They are about 
as smooth as the L. annotinum prothallia, and never as wrinkled 
or lobed as those of L. clavatwm. While the first are yellowish 
brown and the second dark brown, those of L. obscurum are reddish 
brown. They are also somewhat larger than those of the other 
species. The largest one found measured 8X12 _mm.; the smallest 
was about the size of a pin head. Figs. 65 to 71 show them just 
twice the natural size. Owing to the fact that the rhizoids are so 
few that the soil scarcely clings to them, they may be distinguished 
by this means also. The young of the three species just mentioned 
and L. complanatum cannot always be distinguished, but identity 
of species can generally be determined by the habit of growth 
of the endophytic fungus. Confusion of species is sometimes 
