14 
this, but these capsules prove it, for they are constricted below the 
mouth, with brown ridges and loenereeS < stomata, and reflexed 
teeth, united in pairs. 
ORTHOTRICHUM PUSILLUM Mitt. Journ. ian Soc. 8: 25 (1865). 
O. psilocarpum James, Trans. Am. Phil. Soc. 13: 110 (1869). 
From the remarks in the manual it will be seen that James 
admitted the above synonymy, but took exception to the capsule — 
being described as 8-plicate when dry, yet in consulting his 
original description I find the following remarks: 
« This species differs from O. Canadense by the smooth capsule, — 
although at times it appears striate when empty, the capsular — 
walls are nevertheless equal and not at all different at the apparent 
striz, which are produced solely by desiccation.” 
(The O. Canadense referred to is not Schimper’s of 1843, but aq 
Sullivant’s of the Mosses of the U-S., page 33, 1856 O. Ohioense.) : 
On examining S. & L. Musci bor. Am. 180 I find that the ~ 
walls of the capsules, though generally smooth when dry, do show - 
faint traces of the differentiation of the walls into ridges, and in — 
fact 3-4 rows of cells are often longer, thicker and narrower, — 4 
alternating with broad spaces of short quadrangular cells. 
The original description by Mitten calls for one of Drum-_ 
mond’s mosses from Pennsylvania. I find that Number 82 in his 
second set (1841) distributed as O. affine var. pumilum contains 
specimens of O. psilocarpum James, mixed with O. strangulatum 
Sull. The description does not cite any number, but this must 
be the one referred to, as the locality agrees. Sullivant in the 
Icones Supplement says: 
“Mitten’s character of O. pusillum ‘Theca siccitate 8-plicata 
does not agree with this species, in which the capsule is neithe 
plicate nor striate. It represents apparently a different specie 
found intermixed with O. psilocarpum. Specimens communicated a 
by the English author, however, truly represent this last species.” 
Now the explanation of that troublesome quotation is that | 
although Mitten made a mistake in describing the capsule of an- 
other species, probably O. strangulatum, yet most of his description 
and his specimens show that he recognized his species as distinct. 
According to the laws of nomenclature, his name must stand, and 
the main part of his description, for even his mistake is not a bad 
one, as the capsules are occasionally faintly S-ribbed: when dry 
