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1842, Phascum crispum' there are two new species which he names Astomum 
Sullivantii and Astomum nitidulum — he gives no characters — but sent small 
specimens of each — one of them I lost in opening the paper." An empty packet 
in the Sullivant herbarium labeled ''Astomum nitidulum W. P. Schimp. 
{Ast. Sullivantii immixtum Sulliv. misit) W. S. S. Ohio 1842" commemorates 
the loss. Mr. H. N. Dixon has also been so kind as to go through the Schimper 
herbarium at Kew with reference to this matter and finds no type-specimen of 
A. nitidulum preserved as such and no other species mixed with the type- 
specimen of A. Sullivantii. He sends me however copies of drawings found in 
the packet of the type of A. Sullivantii, which, though not labeled, apparently 
represent the lost A. nitidulum. Later specimens labeled A. nitidulum he thinks 
are not specifically separate from A. Sullivantii. The type of A. nitidulum was 
then apparently the bit sent to Sullivant, which is lost. It is possible from the 
brief original description that it contained a somewhat variant capsule of A. 
Sullivantii, but I think much more likely it was a hybrid capsule of Weisia 
viridula upon A. Sullivantii. There is in the Sullivant herbarium a small spe- 
cimen of later collection labeled "Verum Phascum nitidulum Sch. Columbus 
Ohio 1855." I have seen a single plant of this through the kindness of Prof. 
Thaxter and have no doubt that it does agree with the original type, as it does 
in fact with the original description. My conclusion then is that A. nitidulum 
of the S. & L. exsiccati and generally subsequently is synonymous with A. 
Sullivantii, that is with Hymenostomum Muhlenbergianum, but that Schimper 
was probably justified in his original distinction and that his A. nitidiilum was 
presumably of hybrid origin. The whole question of hybrids in this genus I hope 
^ to discuss at greater length subsequently. 
The differences between the European and the American species are quan- 
titative in their nature, as is likely to be the case with closely related cleisto- 
carpous mosses, the American one tending to be smaller in its parts except 
the spores, which are consistently larger and furnish perhaps the clearest and 
most tangible diagnostic character. The relation of diameters is as I find it 
at least 6 to 5, in ^. Sullivantii about 20\x (running up to 25^ or more), in A. 
crispum about lypi. Doubtless abnormal specimens may be found somewhat 
bridging over the gap, but the tendency of the American form to produce larger 
spores is beyond dispute. The larger size of spores marks under the circumstances 
a species farther down in the scale of organization, a more cleistocarpous 
moss. With this the other characters are in accord. The generally smaller 
size of the American species is also shared by the capsule, which futhermore 
has thinner walls, more easily dented out of shape or for that matter broken 
open, letting the light through more readily,*^ showing rather larger exothecial 
* The remarkable difference in this respect shows itself clearly in cross-section of the capsules, 
the European species showing a wall 8-io/i or even more in thickness, with several layers of fairly 
strong cells between it and the spore-sac, and a stronger columella, while the American species 
is only sectioned with difficulty owing to its extremely thin wall (hardly more than i-2/i) and the 
