A. varium forma ovata f. nov. has smaller stem leaves which are more 
concave, round-ovate, abruptly and narrowly short-acuminate with nearly 
the outline of the leaves of Thelia asprella\ quadrate alar cells very num- 
erous, extending - up 1/3 the margin of the leaf. Type in my herbarium 
from near St. Louis, Mo., growing with Eurhynchium hians and Mnium 
cuspidatum. In a way this parallels A. orthocladon but differs from it in its 
more slender costa, more slender acumen and lack of highly colored opaque 
basal cells, as well as in habitat. 
A. noterophilum is to fiuviatile what var. spinifolium is to irriguum, 
a very large form with larger, more elongated leaf cells and strongly excur- 
rent costa. In Europe a corresponding form of filicinum, A. fallax (Brid.) 
Milde, or perhaps better known as filicinum var. Vallis clausae, is found, and 
it is not unlikely that it may occur here also. 
The third subgenus Leptodictyum Schimp. has been raised to the rank 
of a genus by Warnstorf. The species are apparently mostly derivatives of 
A. ripariu7n (L.) B. & S., and besides this species includes A. vacillans 
Sulliv., A. Floridanum R. & C. and three recently described species 
of Cardot and Theriot, A. brachyphyllum and A. brevipes from Minne- 
sota, laxirete from Missiouri. As the three species are admittedly 
closely related to the polymorphous A. riparium, it is probable that most 
authors would regard them merely as varieties. A . vacillans is a rare 
plant with long slender stem leaves having a subobtuse apex and short 
apical cells. I do not believe the large specimens from Georgia and Florida 
that have been referred here (N. Am. Musci Pleurocarpi 269) really belong 
with the northern plant. 
For the convenience of students I will cite corrections of my N. Am. Muse. 
PI. 
No. 48 issued as Hypnum chry sophy llum is my idea of a common form 
of A. Kochii and has so been determined by several eminent authorities. 
No. 243 contains the same with some A. varium. No. 180 issued as A. 
fiuviatile I believe to be A. orthocladon. No. 149 issued as irriguum is 
probably the same. Cheney called it irriguum but Renaud (Fide Dupret) 
thought a similar form belonged rather to fiuviatile. 
No. 177 and No. 266. as A. varium appear to me to be aquatic forms of 
filicinum nearer to irriguum than varium. 
No. 291 issued as varium orthocladon and No. 247 issued as irriguum are 
the large form of irriguum approaching var. spinifolium and certain forms 
of filicinum. No. 130 issued as A. compaction is in my opinion a cespitose 
form of serpens. This had been examined and named by people who ought 
to know and it may be mixed. My set is certainly not compactU7n. 
The fourth group includes A. Lescurii (Sulliv.) only of our species. 
This is characterized by its strongly bordered leaves, but for this it 
would sometimes be difficult to distinguish it from A. orthocladon. It 
rightfully belongs to another genus and should be called Sciarmonium 
Lescurii (Sulliv. ) Broth. 
