CHAP. 37.—THE FINS OF FISH, AND THEIR MODE OF SWIMMING.
Hence it is that there is a difference,[2452] also, in the fins of fish, which have been given them to serve in place of feet, none having more than four,[2453] some two[2454] only, and others none.[2455] It is in Lake Fucinus[2456] only that there is a fish found that has eight fins[2457] for swimming. Those fishes which are long and slimy, have only two at most, such, for instance, as eels and congers: others, again, have none, such as the muræna, which is also without gills.[2458] All these fish[2459] make their way in the sea by an undulatory motion of the body, just as serpents do on land; on dry land, also, they are able to crawl along, and hence those of this nature are more long-lived than the others. Some of the flat-fish, also, have no fins, the pastinacæ,[2460] for instance—for these swim broad-wise—those, also, which are known as the “soft” fish, such as the polypi, for their feet[2461] serve them in stead of fins.