Nor yet are dire and venomous substances found wanting in the sea: such, for instance, as the sea-hare[2762] of the Indian seas, which is even poisonous by the very touch, and immediately produces vomiting and disarrangement of the stomach. In our seas it has the appearance of a shapeless mass, and only resembles the hare in colour; in India it resembles it in its larger size, and in its hair, which is only somewhat coarser: there it is never taken alive. An equally deadly animal is the sea-spider,[2763] which is especially dangerous for a sting which it has on the back: but there is nothing that is more to be dreaded than the sting which protrudes from the tail of the trygon,[2764] by our people known as the pastinaca, a weapon five inches in length. Fixing this in the root of a tree, the fish is able to kill it; it can pierce armour too, just as though with an arrow, and to the strength of iron it adds all the corrosive qualities of poison. CHAP. 73. (49.)—THE MALADIES OF FISHES. We do not find it stated that all kinds of fishes are subject to epizoötic diseases,[2765] like other animals of a wild nature: but it is evidently the fact that individuals[2766] among them are attacked by maladies, from the emaciated appearance that many present, while at the same moment others of the same species are taken quite remarkable for their fatness. CHAP. 74. (50.)—THE GENERATION OF FISHES. The curiosity and wonder which have been excited in mankind by this subject, will not allow me any longer to defer giving an account of the generation of these animals. Fishes couple by rubbing their bellies[2767] against one another; an operation, however, that is performed with such extraordinary celerity as to escape the sight. Dolphins[2768] also, and other animals of the cetaceous kind, couple in a similar manner, though the time occupied in so doing is somewhat longer. The female fish, at the season for coupling, follows the male, and strikes against its belly with its muzzle; while the male in its turn, when the female is about to spawn, follows it and devours[2769] the eggs. But with them, the simple act of coupling is not sufficient[2770] for the purposes of reproduction; it is necessary for the male to pass among the eggs which the female has produced, in order to sprinkle them with its vitalizing fluid. This does not, however, reach all the eggs out of so vast a multitude; indeed, if it did, the seas and lakes would soon be filled, seeing that each female produces these eggs in quantities innumerable.[2771]