156 MONOGRAPH ОЕ CHAETOMIUM AND ASCOTRICHA 
Up to the present time there has been no further attempt too 
make a comprehensive review of the genus or to collate the 
American forms, with the exception of the revision of the Chaeto- 
miaceae by Miss Palliser in the North American Flora, where 
seventeen species are enumerated including three unpublished 
names. | 
The writer feels therefore that а thorough and complete 
study of the subject is much to be desired, and while he cannot 
hope that the following revision can be final, he has spared no 
pains to ascertain the facts in every case so far as has been possible, 
and to make clear by figures and descriptions the specific char- 
acteristics of the individual species which in his opinion should be 
recognized. 
The postponement of the final publication for a considerable 
time on account of unavoidable interruptions and delay caused 
by the preparation of plates seems in the end an advantage, 
for in the course of his work upon these widely distributed fungi, E 
the writer has been able to examine a very large series of specimens. 
from various herbaria and exsiccati, and to cultivate many species - SS 
from diverse sources on various media, over long periods of time | 
and through many successive generations. Аз а result of this ' 
examination, numerous forms һауе been added to those previously Se 
recorded from America, and a number of new species have been- 
recognized. In this connection it may be mentioned that all of X 
these forms, with six exceptions, have been extensively cultivated 52 
in а pure condition and that it has been possible to determine with E 
accuracy their range of variation as well as their salient зресшс 22 | 
characteristics. 71 m 
Those who have given attention to species of Chaefomum — | 
must be aware of the more or less unsatisfactory results 19 be SE 
obtained by working with dry herbarium material. Unless the 
specimens are carefully protected by pill boxes or other convenient 
receptacles, the characteristic appendages of the perithecia Ei 
become broken, and the thin, brittle, perithecial walls disintegrate. 
It is the exception to find herbarium and exsiccati material 
protected. Оп the contrary it is most often mounted on "` 
Page with no protection whatsoever, or enclosed in paper envelope 
Which soon collapse and press against the plants, and it is 
ма ES 
