There are various kinds of crabs,2563 known as carabi,2564 astaci,2565 maiæ,2566 paguri,2567 heracleotici,2568 lions,2569 and others of less note. The carabus differs2570 from other crabs, in having a tail: in Phœnicia they are called hippoi,2571 or horses, being of such extraordinary swiftness, that it is impossible to overtake them. Crabs are long-lived, and have eight feet, all of which are bent obliquely. In the female2572 the first foot is double, in the male single; besides which, the animal has two claws with indented pincers. The upper part only of these fore-feet is moveable, the lower being immoveable: the right claw is the largest in them all.2573 Sometimes they assemble together in large bodies;2574 but as they are unable to cross the mouth of the Euxine, they turn back again and go round by land, and the road by which they travel is to be seen all beaten down with their foot-marks.

The smallest crab of any is that known as the pinnotheres,2575 and hence it is peculiarly exposed to danger; its shrewdness, however, is evinced by its concealing itself in the shell of the oyster; and as it grows larger, it removes to those of a larger size.

Crabs, when alarmed, go backwards as swiftly as when moving forwards. They fight with one another like rams, butting at each other with their horns. They have2576 a mode of curing themselves of the bites of serpents. It is said,2577 that while the sun is passing through the sign of Cancer, the dead bodies of the crabs, which are lying thrown up on the shore, are transformed into serpents.

To the same class2578 also belongs the sea-urchin,2579 which has spines in place of feet;2580 its mode of moving along is to roll like a ball, hence it is that these animals are often found with their prickles rubbed off. Those among them which have the longest spines of all, are known by the name of echinometræ,2581 while at the same time their body is the very smallest. They are not all of them of the same glassy colour; in the vicinity of Torone2582 they are white,2583 with very short spines. The eggs2584 of all of them are bitter, and are five in number; the mouth is situate in the middle of the body, and faces the earth.2585 It is said2586 that these creatures foreknow the approach of a storm at sea, and that they take up little stones with which they cover2587 themselves, and so provide a sort of ballast against their volubility, for they are very unwilling by rolling along to wear away their prickles. As soon as seafaring persons observe this, they at once moor their ship with several anchors.

(32.) To the same genus2588 also belong both land and water2589 snails, which thrust the body forth from their abode, and extend or contract two horns, as it were. They are without eyes,2590 and have, therefore, to feel their way, by means of these horns.

(33.) Sea-scallops2591 are considered to belong to the same class, which also conceal themselves during severe frosts and great heats; the onyches,2592 too, which shine in the dark like fire, and in the mouth even while being eaten.