The Schizæineæ are many of them climbing ferns, and for the most part tropical. Lygodium articulatum climbs trees in New Zealand to the height of fifty or one hundred feet, and its tough wiry stems are used for cordage. In one group of this order, represented by Lygodium, the sporangia are disposed at the back of the frond in imbricated marginal spikes, formed by a transformation of the ultimate pinnæ. In the other division, represented by Schizæa, the fruitful spikes are really on the under-side of the frond, but the frond being reversed they seem to be on the upper. The Ceratopteridineæ, sometimes called Parkeriaceæ, are tropical aquatic ferns, whose sterile fronds, which are membranaceous, with a thick vascular footstalk, float on the surface of the water, and by the time these are nearly decayed the fertile fronds are perfected. The latter are more erect, repeatedly divided and forked, the divisions being linear. There is only a single genus, Ceratopteris, which has continuous sori occupying the longitudinal veins at the edge of the frond, and covered by the indusioid margin. The sporangia have a very broad incomplete ring, and connect the ringless ferns with the group which possess them. The spores are triangular, and marked with three sets of concentric ridges. The order Osmundineæ contains the Osmunda regalis, considered to be the finest of all European ferns, which is common throughout Great Britain in wet spongy soils, and appears to be the only species of the group that is European. The fronds grow in tufts from a thick woody caudex, which branches and extends widely by the formation of lateral crowns, but, if impeded, it elongates and rises in an erect position to the height of two or even three feet above the soil. The barren fronds of the large luxuriant tufts are highly developed, and are from six to nine or even eleven feet high; the fertile fronds are shorter and fewer in number. The bipinnate character prevails throughout; the primary divisions are opposite, the secondary alternate, and the pinnules are oblong and opposite. The sculptured sporangia have a very rudimentary ring, and, in the fruit-bearing fronds, four or five of the lower pairs of pinnules have the leafy character, while the remainder develop clusters of sporangia in place of pinnules. The sporangia on the fruitful branches are at first pale green, but gradually become reddish brown, hence the name of Flowering fern. The Leptopteris section of the genus Todea, almost peculiar to New Zealand, has beautiful transparent fronds, with naked sporangia placed upon the veins, forming very much scattered sori.