The following are the properties of hair and of parts analogous to
hair, and of skin or hide. All viviparous animals furnished with
feet have hair; all oviparous animals furnished with feet have
horn-like tessellates; fishes, and fishes only, have scales-that is,
such oviparous fishes as have the crumbling egg or roe. For of the
lanky fishes, the conger has no such egg, nor the muraena, and the eel
has no egg at all.