In Plate III. the bright-green feathery plant in the extreme background is _Ectocarpus siliculosus_; and behind it, the violet, antler-like fronds of _Nemaleon multifida_. The large, gracefully-bending frond of rich purple, with narrower and younger fronds springing from the same root, is _Porphyra vulgaris_, one of the commonest, but most splendid of our marine _Algæ_, with which, in combination with other plants of suitable contrast, the vegetation of the Aquarium may be rendered truly splendid, if it once be successfully cultivated; of which I have no doubt, when its natural wants are sufficiently studied and ingeniously supplied. The splendidly-marked plant to the right, with its black maculations and richly-frilled edge, is _Nitophyllum punctatum_, one of our most splendid species; and the curious pale-buff, tubular plant in front of it, is _Asperococcus Turneri_. Near the foot of the _Nitophyllum_ is a little tuft of the delicate _Dumontia filiformis_; and, to the extreme left, a branch of the brown-fronded _Rytiphæa pinastris_, which receives its specific name from the somewhat Pine-like growth it frequently assumes. Immediately beneath it, on the extreme right, is a little cluster of _Chordaria divaricata_; and below, in the left foreground, are a few pink fronds of the curious Alga, _Chrysemenia rosea_; while, in the foreground, to the right, on a detached pebble, is a small mass of the pale-crimson _Peyssonetia Dubyi_. In Plate IV. the principal object is a fasciculus of _Taonia atomaria_, rising behind the point of rock at the top of the Plate, behind which are two long fronds of the spotted _Asperococcus_; to the left is the horn-like _Gigartina acicularis_; and in the front, to the left, the crimson tufts of a pretty weed (_Ceramium strictum_), which our artist has made too like the _Bangia fusco-purpurea_.