“The Byssus!” cried Agnes: “I thought that was produced by the Pinna, or Sea-wing. Don’t you remember, mamma, showing me a pair of gloves made of the Byssus of the Pinna at the British Museum? I am sure you said the Pinna.” [Illustration: _Fig. 22._ FRESHWATER MUSSELS (_Dreissena polymorpha_). ] “I remember it perfectly; but other shell-fish produce Byssus besides the Pinna.” “Indeed! and are gloves made of it?” “I believe not; because it is not produced in other shell-fish in sufficient quantities.” “Do not some Mussels produce pearls?” asked Agnes. “Those are the River Mussels,” said Mrs. Merton. “Remember that there are several kinds of Mussels: as, for example, the River Mussel, or Unio, which produces what are called British pearls, and which is common in many British rivers, particularly in the Conway, in Wales, and in the Tay, in Scotland; the Sea Mussel, or Mytilus, the animal of which is eaten, and which produces the Byssus; and the Horse Mussel, or Modiola. The kind you have found, however, belongs to none of these, as it is a freshwater species generally found in docks; and it must have adhered to some vessel that has been shipwrecked here soon after it left the dock in which it had been repaired.” “Oh! mamma, don’t talk of shipwrecks,” cried Agnes, shuddering. They had now reached a little terrace, raised to a considerable height above the beach, where there was a little shop, the proprietor of which sold fruit, and also engravings of various kinds, in the manner which seems fashionable at Shanklin; as the shops there generally contain articles of the most heterogeneous kinds. Here Mrs. Merton inquired the way to the Chine, and they were directed to apply at a little cottage a good way farther up the beach. They did so; and a most uncivil person came out, who, unlocking a gate, told them to go through there, and then left them to find their way how they could. They went straight on along a narrow path, which was exceedingly slippery and disagreeable from the recent rains, and they soon came to a place where the road divided into two, and they did not know which way to take. As Mrs. Merton was very much fatigued by the want of sleep the previous night, Agnes ran forward along one of the paths, while Mrs. Merton waited her return. She soon came back, saying that the path merely led to a seat; but, as she descended the hill, Mrs. Merton noticed that her shoe had burst open behind, and that she had great difficulty in keeping it on her foot. “My dear Agnes,” said her mother, “these shoes were never intended for walking along such roads as these. Why did you not put on your walking-shoes?”