28 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
usually from 2 to 4 mm. in length and 3 to 5 mm. or more in diameter. 
They are decidedly erumpent, rather regular, and subglobose in out- 
line. The contents of the stromata are brick red in color and are very 
powdery when old. 
The stromata of Endothia fluens, E. fluens mississippiensis, and 
E. parasitica resemble each other so closely that the species are prac- 
tically indistinguishable on this basis. All these species are char- 
acterized by partially embedded, confluent stromata which vary 
greatly in outline, depending on the nature of the bark of the host. 
As already stated, they vary from 0.4 to 2 mm. in height and from 
0.7 to 5 mm. or more in length where confluent. £. tropicalis and 
E. longirostris resemble this group in their stromatic characters. 
Pycnidia.—The pycnidia of E'ndothia gyrosa and E’. singularis are 
very distinctive also. The pycnidial cavities of ZL’. gyrosa are narrow 
and so irregularly convoluted that in a section of the stroma the 
cavities vary in width from 0.03 to 0.8 mm., averaging about 0.15 
mm. On the whole, however, they are much narrower than those 
of E. fluens or EL. parasitica. A section of a pycnidial stroma of F. 
gyrosa shows numerous irregular, rounded to elongate chambers 
separated by narrow walls. The pycnidial cavities of EF. singularis 
(Pl. XIII) are minute, 0.03 mm. in diameter, nearly spherical, 
evenly distributed through the stroma and separated at first by com- 
paratively thick walls, which disintegrate and become powdery when 
the stroma is old. 
So far as the writers have been able to determine, the “ tendrils” 
of pycnospores so characteristic of Endothia fluens and £’. parasitica 
are not formed in either Z’. gyrosa or FE’. singularis. Mature pycnidial 
stromata of #.gyrosa when placed in a.moist chamber exude nu- 
merous droplets containing spores and scattered well over the surface 
of the stromata. The writers have been unable to produce any such 
change by placing the pycnidial stromata of F. singularis in moist 
chambers, and it seems probable that the pycnospores of F’. singularis 
are set free by the breaking down of the outer walls of the stromata. 
As already mentioned, the inner partitions are friable, so the spores 
are readily scattered by the wind. 
The pycnidial cavities of Endothia fluens and EF. parasitica, and 
apparently all the other species of this section of the genus, vary 
from 0.2 to 0.8 mm. or more in diameter and may consist of a 
single chamber rather regular in outline (Pl. XIV, fig. 1) or of an 
irregular cavity consisting of many chambers (Pl. XV, fig. 8) more 
or less completely separated from one another. These species differ - 
from £’.. gyrosa in that the pycnospores are usually discharged through 
a single opening near the top of the stroma and emerge in a single 
twisted tendril. 
