I have often sought specimens of this poor relation of the fish-shop window aristocrat, but invariably in vain, until I have found myself suddenly shouting "Eureka!" while balancing myself on one foot eager for the easement of the other, and the giggling demeanour of the imp as it parts company with his spur gives a sort of comic relief to the thrilling sensations of the moment. Upon examination this imp seems to be an example of arrested development. Whimsical fate has played upon it a grim practical joke, flattering it primarily by resemblance to a grotesquely valorous unicorn, and then, having changed her mood to mere pettishness, finished it offhand by adding a section of semi-animate seaweed. Although among the commonest of the species, the grey sand crab, which burrows bolt-holes in the beaches, is by no means an uninteresting character. Surrounded by enemies, and yet living on the bare, coverless beach, its faculties for self-preservation are exceptionally refined. The eyes are elongated ovals, based on singularly mobile pivots, while the pupils resemble the bubble of a spirit-level. Not only is the range of vision a complete circle, but the crab seems able to concentrate its gaze upon any two given points instantly and automatically. To spite all its skill as a digger, to set at naught its superb visual alertness, the sand crab has a special enemy in the bird policeman which patrols the beach. Vigilant and obnoxiously interfering, the policeman has a long and curiously curved beak, designed for probing into the affairs of crabs, and unless the "hatter" has hastily stopped the mouth of its shaft with a bundle of loose sand--which to the prying bird signifies "Out! Please return after lunch!"--will be disposed of with scant ceremony and no grace, for the manners of the policeman are shocking.