| Photo, Ewing Galloway |
| ABOVE, THE GILA MONSTER, FEARED THOUGH ITS BITE IS NOT ALWAYS DEADLY TO MAN BELOW, THE IGUANA, A REMARKABLE LIZARD OF THE NEW WORLD |
The most famous of the rays, probably, are the torpedos, a family with a rounded, instead of the customary triangular outline, and a rather short tail, species of which occur on all tropical and temperate coasts, and are noted for their power to give electric shocks to any living thing touching them.
The electric organs are a pair of large masses lying between the head and the pectoral fins. These are derived mainly from four nerves, which originate from an electric lobe of the medulla oblongata. By means of the electric shocks which they are able to administer at will, the torpedo rays are able to ward off the attacks of enemies, and to kill or paralyze their prey. The action is that of a galvanic battery. The dorsal surface is positive, the ventral negative, and the discharge of a large torpedo is sufficient to temporarily disable a man; yet it is not so powerful as that from a big electric eel.
The huge "sea devils" of which thrilling stories are related are the eagle rays of the family Myliobatidæ, some of which are fifteen or twenty feet across the "wings"; and they are among the most frightful of the dangers to which pearl divers are exposed in their perilous occupation. They are savage beasts, and will even attack a small boat with men in it. The worst of these belong to the vicinity of Panama.
[CHAPTER XVI]
BONY FISHES—TELEOSTOMI
We come now to the fishes proper—those with skeletons of bone, although in some of the lower forms the ossification is incomplete. The mouth contains supplementary tooth-bearing bones that form secondary jaws corresponding to the functional jaws of the higher craniates; hence the group name "Teleostomi," or perfect-mouthed fishes. The body, as a rule, is coated with scales, and a gill cover (operculum) is always present.
The Teleostomi include four orders, the Crossopterygii, the Chondrostei, the Holostei, and the Teleostei.