masses of Corallina oficinalis in the incrusting state. Among the latter were three tufts of Griffithsia setacea, one of Delesseria alata, two of Plocamium coccineum, and one large and one small bush of Phyllophora rubens. To these were added, about ten days afterwards, a mass of Zostera marina.
About 20 gallons of sea-water, dipped from the quay steps while the tide was coming in, were poured into the Tank, a plate being held under the stream, to prevent the displacement of the contents by the falling water. It was rather turbid at first, but soon cleared, and in about two days became quite crystalline, except a slight tinge of green, which always remained; not enough to alter the hue of any object in the vessel, but perceptible, by contrast with the clear air, when the whole body of the fluid was looked through.
No animals were put in till the third day; but from the weeds multitudes of minute creatures swarmed forth, quite peopling the water. At night the application of a candle revealed a vast number of tiny animals clinging to the sides, and visible through the clear glass; Annelides of the genus Syllis; Rissoæ and other minute shell-fish: but principally Isopodous and Entomostracous Crustacea, for the most part so small, as to require a lens for their detection. The careful examination of the water with the triple power of a pocket lens made manifest also that an immense number of Infusoria and some Rotifera were tenanting the Tank.
These, especially the Crustacea, could be drawn to any part of the vessel by the moving of the candle; for when this was placed within an inch or two of the
