Page:Natural History, Fishes.djvu/186

172 fishes, the law which assigns one sphere of action to the Class, is much more uniform in its operation, admitting of scarcely any exception.

This law is not, however, quite universal: there are a few fishes which invade the domain of the birds, as the proper Flying-fishes (Exocœtus), hereafter to be noticed, and some species (Dactylopterus) in the Family of the Gurnards; and in the Lophiadæ, the Family which we have now to describe, a still rarer aberration of habit is found in fishes which are enabled to leave the water, and crawl about on land, for hours, or even days

together, thus emulating the terrestrial manners of quadrupeds.

To enable them to do this, two peculiarities of structure have been conferred upon them: the one modifying the organs of motion, the other those of respiration. The pectoral and the ventral fins in fishes correspond with the limbs of other vertebrate animals, the former representing the arms, fore-legs or wings, the latter the hinder extremities. And this analogy, which is structural, is not at all affected by the relative position of these members, even though the ventrals should be, as in the Family before us, situated