6. For if the external noise is not loud, yet to all aquatic animals that are capable of hearing, it appears harsh and very loud; and this takes place in hunting dolphins, for when they have enclosed them with their canoes, they make a noise from them in the sea, and the dolphins, crowded together, are obliged to leap upon the land, and, being stunned with the noise, are easily captured, although even dolphins have no external organs of hearing. 7. And again in fishing, the fishermen are careful to avoid making a noise with their oars or net when they perceive many fish collected in one place; they make a signal, and let down their nets in such a place that no sound of the oar or the motion of the waters should reach the place where the fish are collected, and the sailors are commanded to row in the greatest silence until they have enclosed them. 8. Sometimes, when they wish to drive them together, they proceed as in dolphin catching, for they make a noise with stones that they may be alarmed and collected together, and thus they are enclosed in a net. Before their inclosure, as it was said, they prevent a noise, but as soon as they have enclosed them, they direct the sailors to shout and make a noise, for they fall down with fear when they hear the noise and tumult. 9. And when the fishers observe large shoals at a distance, collected on the surface in calm, fine weather, and wish to know their size, and of what kind they are, if they can approach them in silence, they avoid their notice, and catch them while they are on the surface. If any noise is made before they reach them, they may be seen in flight. In the rivers, also, there are little fish under the stones, which some persons call cotti:[143] from their dwelling beneath rocks, they catch them by striking the rocks with stones, and the fishes fall down frightened when they hear the noise, being stunned by it. It is evident, from these considerations, that fishes have the sense of hearing. [143] Perhaps Cottus gobio L., miller's thumb. Salmo Fario (_Strack_). 10. There are persons who say that fish have more acute ears than other animals, and that, from dwelling near the sea, they have often remarked it. Those fish which have the most acute ears are the cestreus[144] (chremps),[145] labrax,[146] salpe,[147] chromis,[148] and all such fishes; in others the sense of hearing less acute, because they live in the deeper parts of the ocean. [144] Mullet. [145] Unknown. [146] Perca Labrax. [147] Scomber. [148] Unknown.