CHAP. 33.—GILLS AND SCALES.
Some fishes have numerous gills, others again single[2433] ones, others double; it is by means of these that they discharge the water that has entered the mouth. A sign of old age[2434] is the hardness of the scales, which are not alike in all. There are two lakes[2435] of Italy at the foot of the Alps, called Larius and Verbanus, in which there are to be seen every year, at the rising of the Vergiliæ,[2436] fish remarkable for the number of their scales, and the exceeding sharpness[2437] of them, strongly resembling hob-nails[2438] in appearance; these fish, however, are only to be seen during that month,[2439] and no longer.