after growing and branching as polyps, give rise to little jelly-fish here and there on the tree, which in most kinds (though not in all) break off and swim away freely. CHAPTER XII SHRIMPS, CRABS, AND BARNACLES WE have no word in English to indicate the varied crab-and-shrimp-like creatures of salt and fresh waters in the same way as "insect" designates the six-legged, usually winged, terrestrial creatures of many kinds--beetles, bees, bugs, two-winged flies, dragonflies, day-flies, and butterflies. They are all "insects." Naturalists call the aquatic shrimp-and-crab creatures "crustaceans." Perhaps "crab" might be used in a large sense to include them all, together with the true crabs, as the Germans use their word, "krebs." The shore-crab is the most familiar of all crustaceans, in the living, moving condition. Boiled lobsters, prawns, and shrimps are more generally familiar members of the class, but the "undressed" living crab is better known to every one who has been on the seashore than the live lobster, prawn, and shrimp. Londoners have been heard to express interest in the curious blue variety of lobster caught on the coast, not being aware that the hot bath which he takes before he, too, is "dressed," causes his blue armour to change its colour to a brilliant scarlet. Occasionally a regular ordinary lobster is caught in which this change has occurred during life in the sea--and there are some enormous deep-sea prawns of a pound in weight which when living have a splendid crimson colour. A large series of "crustaceans," carefully prepared so as to show their natural colours in life, is exhibited in the Natural History Museum in Cromwell Road.