An oyster (OSTREA DENDOSTREA FOLIUM), too mean of proportions, too dull and commonplace of colour to be termed pretty, worth nothing, and justifying, in appearances its worthlessness, is remarkable for the exercise of a certain sort of deliberate wit in accordance with special conditions. Nature provides various species of the great oyster family with respective methods of holding their own in the sea, and in the case under review she permits the individual to exercise a choice of two different methods of fixture as chance and the drift of circumstances decide its location. From the bases of the valves spring three or more pairs of hook-like processes which, if Fate decides upon a certain coral host, encircle a slim "twig," creating for the mollusc a curious resemblance to a short-limbed sloth hugging tightly the branch of a tree. When the spat happens to settle in places where coral is not available the hooks or arms are but crudely developed. It becomes a club-footed cripple, its feet adherent by agglutination or fusion to a rock or other and larger mollusc, dead or alive. In fact, the shrewd little oyster responds to its environment, clasping a twig with claws or cementing itself to an unembraceable host in accordance as contingencies insist.
Another mollusc (AVICULA LATA), sometimes found in company with the clinging oyster, resembles, when the fragile valves are expanded, a decapitated butterfly, brick-red in colour, with an overshirt of fine and elaborate network, orange tinted. The interior is scarcely less attractive, the nacre having a pink and bluish lustre, while the "lip" is dark red. This is found (in my experience) only in association with a certain species of coral (GORGONIA), which flourishes in strong currents on a stony bottom three or four fathoms deep. Apart from the unusual shape and pleasing colours of the shell, it is remarkable because it seems to be actually incorporated with its host. The foot of the mollusc is extended into a peduncle, consisting of fibres and tendons, by which the animal is a fixture to a spur of coral. At the point of union (to facilitate which there is a hiatus in the margins of the peduncle) the sarcode or "flesh" of the coral is denuded, its place being occupied by ligaments, which by minute ramifications adhere so intimately to the coral stock or stem that severance therefrom cannot be effected without loss of life to the mollusc.