There is another kind of flat fish, which, instead of bones, has cartilage, such, for instance, as the raia,2481 the pastinaca,2482 the squatina,2483 the torpedo,2484 and those which, under their respective Greek names, are known as the ox,2485 the lamia,2486 the eagle,2487 and the frog.2488 In this number, also, the squali2489 ought to be included, although they are not flat fish. Aristotle was the first to call these fish by the one generic name of σελάχη,2490 which he has given them: we, however, have no mode of distinguishing them, unless, indeed, we choose to call them the “cartilaginous” fishes. All these fish are carnivorous,2491 and feed lying on their backs, just as dolphins do, as already2492 noticed; while the other fishes,2493 too, are oviparous, this one kind, with the exception of that known as the sea-frog, is viviparous, like the cetacea.2494