That the barnacles--ship's barnacles (Fig. 10) and with them the little sea-acorns (Fig. 11), those terribly hard and sharp little white "pimples" which cover the rocks nearly everywhere just below high-tide mark, and have so cruelly lacerated the hands and shins of all of us who swim and have had to return to a rocky shore in a lively sea--should be included with crabs, lobsters, and shrimps as "crustaceans" must appear astonishing to every one who hears it for the first time. The extraordinarily ignorant, yet in their own estimation learned, fishermen of the Scottish coast will tell you with solemn assurance that the ubiquitous encrusting sea-acorns are the young of the limpet, whilst the creature living inside the shell of the long-stalked ship's barnacles has for ages been discoursed of by the learned as one of the marvels of the sea--nothing more or less than a young bird--the young, in fact, of a goose--the barnacle goose which, since it was thus proved to be a fish in origin, was allowed to be eaten by good Catholics on fast days! Two hundred years or more ago this story was discredited by serious naturalists, but the barnacles and sea-acorns were thought (even by the great Cuvier) to be of the nature of oysters, mussels, and clams (Molluscs), because of their possessing white hard shells in the form of "valves" and plates, which can open and shut like those of mussels. Their true history and nature were shown about eighty years ago by a great discoverer of new things concerning marine creatures, Dr. Vaughan Thompson, who was Army Medical Inspector at Cork, and studied these and other animals found in the waters of Queenstown Harbour.