but did not adhere: by degrees the pulp dries up, and in the ripe capsule leaves only the membrane or tympanum of an inorganic appearance, and firmly cohering with the teeth by the inner side of their apices. It does not therefore [319 properly belong to the operculum, though in some cases it may adhere to it, as does the analogous process of the columella in Dawsonia and in several other mosses.
The affinity of Dawsonia to Buxbaumia is certainly less strict than to Polytrichum, and rests chiefly on the similarity of the figure of the capsule, and in the central process of the columella, which is still more evident in Buxbaumia, where it forms part of the Linnean generic character, though unaccountably overlooked by Schmidel in his masterly dissertation; but, if I mistake not, actually represented by him [in fig. 14, b[1]], and confounded with the peristomium, which in this case, I suppose, had adhered to the operculum, as I have repeatedly found it to do, and thus escaped his notice. Hedwig considers the plaited membrane which constitutes the peristomium of Buxhaumia, as derived from the inner membrane of the capsule, and quotes the figure just mentioned of Schmidel in proof of this origin. In both species, however, I find it arising from the exterior membrane, though considerably within its margin, which in Buxbaumia aphylla is said by Hedwig to be divided into teeth,—an appearance I could not observe in the few ripe capsules I have dissected. In other respects, the two species seem essentially to agree, and therefore ought not to be separated, as Ehrhart and some late writers have done. The generic character comprehending both, I would propose to alter in the following manner.
BUXBAUMIA.
Capsula obliqua, hìnc convexior, vel gibba.
Peristomium intra marginem, quandoque dentatum, membranæ exterioris ortum, tubulosum, plicatum, apice apertum.
- ↑ Schmidel, Dissertationes Botanici Argumenti.
