The Prawn takes its food with its _second_ feet, two-fingered hands or claws, and carries it to its mouth. The hands of the _first_ pair of legs are only rudimental in appearance, but are precisely fitted to their special purpose. They are his cleansing apparatus; and it is most interesting to watch the operations of his toilet when he uses these fringes as brushes, with which he cleanses his whole person most thoroughly, being almost unmerciful in the amount of severe scrubbing to which he subjects himself. An allied species, _P. squilla_, is scarcely distinguishable from _P. serratus_; but the handsome scarlet-striped Prawn, _Pardulus annuticornis_, about the size of a Shrimp, is quite distinct, and would make a valuable addition to the collection. The Lobster Prawn, also, _Athanas nilescens_, has likewise been tried. Some kinds of Crabs may be admitted, but not many; for several are extremely voracious, and would soon clear off all the naked Zoöphytes and most of the Molluscs. The Climbing Crab, _Eurynome aspera_, is interesting in a tank from his habits. His climbing is as graceful and skilful as that of a monkey, and when he has succeeded in perching himself upon the highest object in the tank, he forms a picturesque object. Crabs, like Prawns, are sea-scavengers, and the kinds that do not attack living creatures as well as dead are consequently useful in a tank. The great Fiddler Crab, _Portunus puber_, is remarkably handsome. He is clothed, in part, with a velvety brown fur, and the bare places of his shell are of a shining black. His eyes are marked with scarlet, and there are a few touches of bright blue about the head. If introduced, his proceedings should be carefully watched. There should certainly be a specimen of the Hermit Crab in a Whelk-shell; and the Cleanser Crab, _Portunus depurator_, has been tried, but these active and greedy Sea-Spiders must be closely looked after. It remains to speak of the Star-Fish tribe, which affords some of the most beautiful and easily managed subjects for the Aquarium. In the centre of the lower part of Plate VI. are a large and a small specimen of the beautiful scarlet species, _Geniaster equestres_; just above, to the right, the graceful pink _Cribella oculata_; further to the right, _Asteria gibbosa_; and immediately above the _Cribella_, the thin, leathery species, the bird’s foot Sea-Star, _Palmipes membranaceus_. All these species are small, easily managed, and especially suited to the Aquarium; as is also the finely-marked and long-rayed _Ophicoma rosula_, his deep scarlet, with bright black marks, and his slender limbs or rays, rendering him a conspicuous object. These Star-Fish glide round the Aquarium, by the aid of their thousand sucker-like feet, in a very interesting manner.