The Trochus tribe, better known as Tops, are also useful as cleaners, and in appearance are more stately and ornamental than the winkle, their cleanly marked conical shell attracting as much attention from strange eyes as the noble planorbis corneus does in the river-tank. Generally speaking, univalves are more easily kept than bivalves; many of the latter are apt to die off, and cause some amount of putrescence before their demise is discovered.
Crustacea are lively and interesting, but of course small species, or small specimens of large species are the most suitable. The Soldier crabs (Pagurus) and the Swimming crabs (Portunus) are eminently suitable, so is the pretty Strawberry crab, Eurynome aspera, and the interesting Broad-claw Porcellana platycheles. Shrimps and prawns may be used freely; they are lively creatures, and much more beautiful when seen in motion, gliding about like ghosts, than would be imagined by any one judging from the appearance of specimens on the table.
CARCINAS MÆNAS.
Annelides afford us the interesting serpulas, some pretty sea-worms, and the terebellas, all easy of preservation, and remunerative of the attention bestowed upon them.
Zoophytes.—This is the division from which the most prominent attractions of the tank are derived. Of these the Actinia take precedence of all the ordinary inhabitants of the tank, because of their exquisite beauty, strange habits, and still more general certainty attending their preservation.
Actinia mesembryanthemum is the common Smooth Anemone which abounds on every part of our coast. Its colour varies considerably, but it is usually of a deep, warm chocolate, dotted all over with small yellow spots, and when closed has the best possible resemblance to a large ripe strawberry. Every stone about the sea-beach is studded with this anemone, and a collector may secure any required number in a few hours, slipping each from its base, and dropping the whole into a jar with some fragments of fresh wet weed to keep them moist.
When it expands, a circle of bright blue beads, or tubercules, resembling torquoises, is seen just within the central opening; and, as the expansion proceeds, a number of coral-like fingers, or tentacles, unfold from the centre, and at last spread out on all sides like the hundred petals of a Peri flower, reminding one of Hinda's boon:—
----Be it our's to embellish thy pillow
With everything beauteous that grows in the deep;
Each flower of the rock, and each gem of the billow,
Shall sweeten thy bed and illumine thy sleep.
Around thee shall glisten the loveliest amber
That ever the sorrowing sea-bird has wept,
With many a shell in whose hollow-wreathed chamber
We, Peris of Ocean, by moonlight have slept.