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North American species.^ That the two continents should not exactly agree 
in this genus is not greatly to be wondered at. The Dicranaceae, in the broad 
sense of Brotherus, are largely boreal mosses with close circumpolar agreement 
of species. The Pottiaceae of Brotherus, in which he includes Astomum, are on 
the other hand very generally types of warmer latitudes and adapted to habitats 
with a hot, dry season. Agreement of species between Europe and North 
America is in this group not nearly so close. As to Astomum in particular, 
it does not in America extend north of the limits of the United States except in 
a single locality in the Saskatchewan region, where it has not been found since 
Drummond's day. It is a plant of open fields, not of forests or mountains. 
Furthermore according to the theory generally held at present with reference to 
cleistocarpous mosses they are for the most part, if not altogether, relatively 
young phylogenetic types, not replicts of early stages in bryologic evolution. 
This is obviously true of Astomum and explains in part why its species are in 
such a plastic state, so hard to grasp in their range of variation and to separate 
clearly from one another. 
Hymenostomum Muhlenbergianum (Swartz) new combination. The 
earliest name for our common species is Phascum Muhlenbergianum Swartz. The 
name was published after Swartz' death (1818) in the " Adnotationes botanicae" 
edited by J. E. Wikstr5m and published at Stockholm in 1829 (pp. 74f.). 
According to the preface (p. VI) Swartz received plants from Muhlenberg in 
1810 and 181 1. Muhlenberg in fact included the new name in his "Catalog" 
of 1813, but without accompanying description, though according to Swartz' 
p)reface the description had also been sent him. As to the type-specimen, 
I have on two different occasions gone through the Muhlenberg moss-her- 
barium at the Academy of Natural Sciences in Philadelphia. Thanks particularly 
to Mrs. Britton 's work of revision the collection is in good shape for study. It 
contains a number of cleistocarpous mosses labeled Phascum, some of which are 
clearly referable to Astomum, but none is labeled Phascum Muhlenbergianum 
and it is perhaps a question whether Muhlenberg retained duplicates in the 
strict sense of specimens sent away for examination. His specimens are very 
meagre and accompanied by little or no data. Drummond , who saw his collection 
while on his second American collecting trip, calls them'" miserable ".^ During 
the war years it was difficult for me to get information, to say nothing of specimens, 
3 Grout (Mosses with Handlens and Microscope, 139- 1904) speaks also of a single specimen 
of A. crispum which he had seen from the northern States, with several from the southern ones. 
Apart from the improbability that our endemic species would be of more northerly distribution 
than the one common to Europe, I have been unable to identify any of our southern specimens 
with A. crispum, but have felt justified in referring them all to either A. Sullivantii or A. ludo- 
vicianum. It is possibly puzzling forms of the latter with abbreviated seta and general poor 
development that have suggested A. crispum, though such forms are not common. I would 
emphasize that apart from this minor point, I find myself in entire agreement with Grout and 
believe he had correctly grasped the essential facts with reference to our northeastern Astomum. 
* Hooker, Journal of Botany, I, 54. 1834 (letter of Apr. 28, 1831). 
