4. Rhizocarpeæ—Water ferns.
5. Selaginellales.
II. PHANEROGAMIA.
(a) GYMNOSPERMIA.
1. Cycadeæ—Cycads.
2. Coniferæ—Cone-bearing trees.
b) ANGIOSPERMS.
1. Monocotyledons.
2. Dicotyledons.
We have now to deal more particularly with those marine Algæ that are commonly known as Sea Weeds, and which add so much to the beauty of our rocky coasts. These exhibit such a variety of graceful forms, and such charming colours, that they are admired and treasured by thousands of sea-side ramblers, who are attracted by them merely on account of their pleasing general appearance; but the naturalist has all this and a great deal more to interest and instruct him, for the sea weeds possess quite a number of peculiar and characteristic features that render them well worthy of a detailed study, especially when they are compared and contrasted with the better-known flowering plants of our fields, woods, and hedgerows.