Those animals, however, it must be admitted, which lie enclosed in a stony shell, have no sensation whatever—such as the oyster,2753 for instance. Many, again, have the same nature as vegetables; such as the holothuria,2754 the pulmones,2755 and the sea-stars.2756 Indeed, I may say that there is no land production which has not its like in the sea;2757 no, not even those insects which frequent our public-houses2758 in summer, and are so troublesome with their nimble leaps, nor yet those which more especially make the human hair their place of refuge; for these are often drawn up in a mass2759 collected around the bait. This, too, is supposed to be the reason why the sleep of fish is sometimes so troubled in the night. Upon some fish, indeed, these animals breed2760 as parasites: among these, we find the fish known as the chalcis.2761