On the upper left-hand portion of the illustration may be seen a long, fat, hairy creature, called popularly the Sea-mouse, and known to zoologists as _Aphrodite aculeata_. Although it inhabits the mud--and sea-mud is about as noisome a substance as can be imagined--it is clothed with a garment of such beauty that the rainbow itself can scarcely rival, and not surpass it. The hairs with which it is so profusely covered glitter and sparkle with every imaginable hue, among which red and green seem to be predominant. These hairs occupy the sides of the body, but in the upper surface there is a thick coating of felted hairs, interwoven with each other so closely that they can with difficulty be separated. These hairs form a natural filter, strain away the mud from the water, and allow the latter to pour itself upon the organs of respiration. If, therefore, a specimen be examined when it is first brought up by the dredge, the felted hair will always be found to contain a considerable amount of mud, and much washing is needed before the creature can be introduced into an aquarium where the water is intended to be transparent. [Illustration: APHRODITE. DUCK’S BEAK.] [Illustration: FILTER.] I may here mention that the name of Aphrodite is a singularly happy one. It signifies something that arises from the foam of the sea, and was given to the goddess of beauty, because in the ancient myths she was said to have sprung from the foam of the sea. Unpoetical as it may appear, the German word Meerschaum, which is so familiar to us in connection with pipes, is the exact equivalent of Aphrodite. * * * * * BELOW the Aphrodite is a figure representing the filtering apparatus which is found in the beak of the duck. This singularly beautiful apparatus is well worthy of examination, and the more important details of its structure can easily be made out by the unassisted eye. In the first place, the upper half of the beak, or upper mandible, as it is scientifically called, is furnished along its edges with a row of curved horny projections, very like the teeth of a comb, and each of them coming to a point. There are some fifty or sixty of these teeth on each side, and they are regularly graduated in size, being longest in the middle of the beak, and becoming very short at either end. They are set diagonally, with the tips pointing backwards. The edges of the lower mandible are turned up in a sort of fold, on the outside of which is a row of grooves corresponding with the teeth of the upper mandible, and, like them, being set diagonally.