In Plate V. the violet-toned _Laurencia pinnatifolia_ is grouped behind the solid, deep-crimson fronds of _Iridæa edulis_, which are often perfectly Pear-shaped, like pieces of crimson leather neatly cut in that form; but the action of tides in rough weather often tears the edges, and wears holes through the texture of the plant, as shown in the principal frond. To the left is the bright-crimson _Rhodymenia lacinata_—one of our most exquisitely beautiful marine _Algæ_. The fronds are as thin as the finest conceivable tissue, and beautifully transparent, which is shown wherever the lacinations of the edge overlap each other, in which places the double thickness of the texture doubles, at the same time, the intensity of the colour, as indicated in the representation. On the same level, to the right, is a small group of the delicate green _Ulva latissima_—a plant which has proved useful beyond all others in Aquaria, as throwing off, under the action of the light, a much greater profusion of silvery globules of oxygen than any other species yet known. At the same level still, on the extreme right, is a sprig of the delicately-branched parasite, _Polysphonia parasitica_, growing on a small mass of pale sulphur-coloured _Melobesia lichenoides_, the Lichen-like Melobesia. To the extreme left, under the beautiful _Rhodymenia_, is a small branch of the bright, olive-tinted _Ectocarpus tomentosus_, looking much like a spray of wild Broom, and immediately below it, a few purple branchlets of _Gracilaria confervoides_; while in the left foreground lies a pebble, partly covered by a small plant of _Zonaria parvula_, from beneath which straggles a little branch of the common but pretty Coralline, the _Corallina officinalis_; and, to the right, a globe of the curious _Codium bursa_, of the French coast, which might easily be added to our native species in the Aquarium. [Illustration: PLATE III. 1. Porphyra vulgaris. 2. Dumontia filiformis. 3. Asperococcus Turneri. 4. Rytiphlæa pinastris. 5. Chrysymenia rosea. 6. Peyssonetia Dubyi. 7. Chordaria divaricata. 8. Ectocarpus siliculosus. 9. Nemaleon multifida. 10. Nitophyllum punctatum.] Such are a few of our beautiful coast _Algæ_, all of which I would advise the admirers of the beauties of the marine Aquarium to try; and if some refuse, in the present state of our knowledge of their habits and requirements, to make themselves happy in their pretty “crystal palace,” choosing rather to consider it a “prison of glass,” still a good number of them, I am persuaded, may be coaxed into displaying their beauties very genially within its transparent walls, which admit the bright sun rays as freely as the pale-green liquid glass which forms their native element.