“The cause of these attacks is not very well ascertained; they have in turn been ascribed to the presence of the coppery pyrites in the neighbourhood of the mussel; to certain small crabs which lodge themselves as parasites in the shell of the mussel; to the spawn of star‐fish or medusæ that the mussel may have swallowed. But, probably the true cause of this kind of poisoning is found in the predisposition of individuals. The remedy is very simple; an emetic, accompanied by drinking plentifully of slightly acidulated beverage.” They are eaten very freely in most parts of the seaboard of the United States, and the present writer has eaten them constantly, boiled, stewed with tomatoes, &c., and in soup, without the slightest bad effects. [Illustration: ISOLATED PILES COVERED WITH THE SPAWN OF MUSSELS.] _The_ bivalve _par excellence_ must always be _Ostrea edulis_, the common oyster. This mollusc, which some might be inclined to place low in the scale of nature, has really a complex and delicate organisation. It has a mouth, heart, stomach, liver, and intestines; its blood is colourless, but it has a true circulation; and it breathes under water, as do fishes. “Having no head,” says Figuier, “the oyster can have no brain; the nerves originate near the mouth, where a great ganglion is visible, whence issue a pair of nerves which distribute themselves in the regions of the stomach and liver, terminating in a second ganglion, situated behind the liver. The first nervous branch distributes its sensibility to the mouth and tentacles; the second, to the respiratory branchiæ. With organs of the senses oysters are unprovided. Condemned to a sedentary life, riveted to a rock, where they have been rooted, as it were, in their infancy, they neither see nor hear; touch appears to be their only sense, and that is placed in the labial tentacles of the mouth.” The oyster may carry hundreds of thousands of eggs—some say as many as 2,000,000; it ejects them after a process of incubation. Nothing is more curious than to witness a bank of oysters in the spawning season, which is usually from the month of June to the end of September.(35) Every adult—for the oyster is sexless—throws forth a living dust, a perfect cloud of embryotic life. The spat is soon scattered far and wide, and unless the young oyster attach itself to some solid body, it falls a victim to other marine animals. Microscopic in size when it leaves the parent, it is at the end of a month about the size of a large pea; in a year it may be an inch and a half in diameter; in three it is getting on to a quite respectable size, and after a short course in the oyster park it is ready for the table.(36)