The plants in most flourishing condition in the marine tanks of the Zoological Gardens, were at first those of the _Chlorospermatous_ order, but others have since succeeded nearly as well. Plants of _Ulva_ and _Conferva_ have done very well, but the most successful growth has been that of a plant of the genus _Bryopsis_, which, entirely enveloping a large stone in its mossy and almost feather-like foliage, produces a very beautiful appearance. Those unlearned in scientific names will be glad, perhaps, to learn that these beautiful _Algæ_ derive their title from two Greek words, Bryon (βρυον), a moss, and opsis (οψιϛ), a resemblance, from their likeness to some of the most delicate and feather-like mosses of our woods. The delineation of _Bryopsis plumosa_ in Plate II., on the extreme left near the lower part of the Plate, will convey some idea of these elegant sea-weeds. _Chondrus crispus_ is a beautiful plant, and well suited to the Aquarium. It will often be found under ledges of rock, completely concealed by a pendant veil of _Fucus_, commonly known as the olive-weed; and, on lifting the tangled mass of its rank growth, many beautiful and unexpected plants are frequently found, but none strike the explorer more than the _Chondrus_. Its nacreous tints, like those of a pearl shell, varying wonderfully according to situation, being very remarkable. It is the Carrageen Moss of the herb market. This plant forms the principal object in the lower part of Plate IV., to the right. _Laurencia pinnatifolia_ is a pretty branching plant, also varying in hue according to the aspect in which it grows. In the shade it is purple, but when receiving the full influence of the sun’s rays, it assumes a light-yellow tone; just as the _Lycopodium_, known as Fortune’s Moss, is purple when grown in the darkest part of a room, but becomes of an ordinary green tone when placed for some time near the light. The _Laurencia_ is shown at the upper part of Plate V., coloured pale-violet.