2. Musci. Mosses, which have real separate leaves, and often a stem; a hood-like corolla, or calyptra, bearing the style, and concealing the capsule, which at length rises on a stalk with the calyptra, and opens by a lid.
3. Hepaticæ. Liverworts, whose herb is a frond, being leaf and stem united, and whose capsules do not open with a lid. Linnæus comprehends this Order under the following.
4. Algæ. Flags, whose herb is likewise a frond, and whose seeds are imbedded, either in its very substance, or in the disk of some appropriate receptacle.
5. Fungi. Mushrooms, destitute of herbage, bearing their fructification in a fleshy substance.
Such are the principles of the Linnæan Classes and Orders, which have the advantage of all other systems in facility, if not conformity to the arrangement of nature; the latter merit they do not claim. They are happily founded on two organs, not only essential to a plant, but both necessarily pre-
