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Rh by a circumstance that he does not seem to have noticed, namely, that his outer peristomium, the corona of Hedwig, consists of a double series of cilia. The number of cilia in each series exceeds sixteen, but hardly amounts to thirty-two; it probably, however, corresponds with that of the plicæ in the membranaceous peristomium.

We have here then a passage from a number still perhaps definite, though disposed in a triple series, to the indefinite number peculiar to, and so striking in, Dawsonia.

My second observation relates to the inner membrane of the capsule, of which I find the mouth to be quite entire and open, though before the separation of the operculum it is closed by the terminating process of the columella. Hence Buxbaumia has some resemblance to Polytrichum, and a still greater to Lyellia, in this part of its structure.

Buxbaumia aphylla is the only moss considered as being entirely destitute of leaves; and though it has been oftener and more fully described than any other plant of the order, from the monographs of Linnæus and Schmidel to the excellent illustration recently published by Mr. Hooker, there is no difference of opinion on this point. I have lately ascertained, however, that Buxbaumia aphylla is always furnished with perfect leaves, which more nearly resemble, both in texture and division, those of a Jungermannia than of any species of moss properly so called; and consequently are widely different from those of Polytrichoïdeæ, to which this genus is in several respects related.

The leaves in the barren plant, where I first observed them, are lanceolate and but slightly divided. Those at the base of the female perichætium are even broader than the former, but more deeply cut, both laterally and at top, into several capillary segments; while the leaves which proceed from the surface of the perichætium are still more deeply divided, and their segments so much elongated that the minute foliaceous base has been universally overlooked, and the perichætium consequently described as covered with hairs.