CHAP. 66. (42.)—THE PINNA, AND THE PINNOTHERES.

Belonging to the shell-fish tribe there is the pinna[1] also: it is found[2] in slimy spots, always lying upright, and never without a companion, which some writers call the pinnotheres,[3] and others, again, pinnophylax, being a small kind of shrimp, or else a parasitical crab. The pinna,[4] which is destitute of sight, opens its shell, and in so doing exposes its body within to the attacks of the small fish, which immediately rush upon it, and finding that they can do so with impunity, become bolder and bolder, till at last they quite fill the shell. The pinnotheres, looking out for the opportunity, gives notice to the pinna at the critical moment by a gentle bite, upon which the other instantly closes its shell, and so kills whatever it has caught there; after which, it divides the spoil with its companion.

1. Or pina. The Pinna marina, Cuvier says, is a large bivalve shell-fish, which is remarkable for its fine silky hair, by means of which it fastens itself to the bottom of the sea.

2. The poet Oppian, Halieut. B. ii. 1. 186, relates the same story about the pinna and its protector; which is also mentioned by Cicero, Plutarch, and Aristotle.

3. We have already had an account of one pinnotheres, in c. 51. Some of the editions, however, make a difference in the spelling of the name, and call the animal mentioned in the 51st Chapter, "pinnotheres," and the one here spoken of, the "pinnoteres," the "guardian of the pinna;" from the Greek verb thre/w, "to keep," or "guard." "Pinnophylax" has the same meaning.

4. Cuvier says, that in the shell of the pinna, as, in fact, of all the bivalves, there are often found little crabs, which are, as it were, imprisoned there; and that it is this fact that has given rise to the story of the treaty of amity between these two animals, which appears in various authors, and is related in various forms, which only agree in being devoid of truth. Cuvier says that a careful distinction must be made between the pinnotheres of this Chapter, the one of which Aristotle makes mention, and that which is mentioned by Pliny in c. 51, the hermit-crab of the moderns. There can, however, be but little doubt that they are different accounts of the same animal.