The tribe Splachnei contain many of the most singular and beautiful of the whole class of mosses. They have large-celled diaphanous leaves and a straight urn, with the spores radiating from the columella. The urn has a swelling at its base, often of greater dimensions than the urn itself. In the Splachnum vasculosum it is purple and very large, but nothing in comparison of that organ in S. luteum and rubrum, which are the pride of hyperborean Europe and America. The enormous size of the swelling, the variety of colouring, the singularity and elegance of form, and in some cases the unusual dimensions, make the species objects of great interest. The common S. ampullaceum, when growing in abundance on the shallow peaty banks of some mountain stream where cattle come to drink, is scarcely exceeded in beauty by any cryptogam. Species of this order are abundant in the two hemispheres, but the same species rarely occur in both. Their habits, too, are different, for while those in the north only grow on manure, those in the south grow on the trunks of fallen trees. Three genera occur in Great Britain. Gemmæ are found in the axils of the leaves in most species of this group. The tribe of Schistostegei consists of but a single most elegant species. It inhabits shady caverns, which are sometimes lighted by a golden gleam from the refractions of the confervoid shoots of its mycelium-like pro-embryo, which is perennial, and produces a new crop year after year. The urn is subglobose without a peristome, and when young the spore cells radiate from the columella as in the Splachna. The leaves show various intermediate stages between a vertical and horizontal insertion, and are sometimes perfectly free, while at other times they are united. This moss is scarce, and confined to the northern hemisphere. There are various genera of aquatic mosses in the different tribes, most of them floating plants. Of these are the pleurocarpous Fontinalei, which inhabit the northern hemisphere; their urn, with its double peristome of sixteen teeth, forms a beautiful microscopic object, on account of the latticed work in the inner row, and the cross bars on the outer teeth, which are united at their tips by two and two. The common species have sharp-angled triangular stems, and keeled leaves which clasp the stem at their base, and are sometimes cleft along the keel.