37. But Apollodorus the Athenian, in his Commentaries on Sophron, having first quoted the saying, "More greedy than a purple-fish," says that it is a proverb, and that some say that it applies to the dye of purple; for that whatever that dye touches it attracts to itself, and that it imbues everything which is placed near it with the brilliancy of its colour: but others say that it applies to the animal. "And they are caught," says Aristotle, "in the spring; but they are not caught during the dog-days, for then they do not feed, but conceal themselves and bury themselves in holes; and they have a mark like a flower on them between the belly and the throat. The fish called the ceryx has a covering of nearly the same sort as all the other animals of the snail kind from its earliest birth; and they feed by putting out what we call their shell from under this covering. And the purple-fish has a tongue of the size of a finger or larger, by which it feeds; and it pierces even shell-fish, and can pierce its own shell. But the purple-fish is very long-lived; and so is the ceryx: they live about six years, and their growth is known by the rings in their shell. But cockles, and cheme-cockles, and solens, and periwinkles, are born in sandy places. 38. But the pinnæ spring from the bottom of the sea. And they have with them a fish called the pinnophylax, or guard of the pinna, which some call καρίδιος, and others καρκίνιος; and if they lose him, they are soon destroyed. But Pamphilus the Alexandrian, in his treatise on Names, says that he is born at the same time with the pinna. But Chrysippus the Solensian, in the fifth book of his treatise on the Beautiful and Pleasure, says, "The pinna and the guard of the pinna assist one another, not being able to remain apart. Now the pinna is a kind of oyster, but the guard of the pinna is a small crab: and the pinna having opened its shell, remains quiet, watching the fish who are coming towards it; but the guard of the pinna, standing by when anything comes near, bites the pinna, so as to give it a sort of sign; and the pinna being bitten, closes its shell, and in this manner the two share together what is caught inside the pinna's shell. But some say that the guard is born at the same time as the pinna, and that they originate in one seed." And again, Aristotle says, "All the fish of the oyster kind are generated in the mud,--oysters in slimy mud, cockles in sandy mud, and so on; but the small oyster and the balanus, and other fish which come near the surface, such as limpets and periwinkles, are born in the fissures of the rocks. And some fish which have not shells are born in the same way as those which have shells,--as the sea-nettle, the sponge, and others,--in the crevices of the rocks."