Fishes . generic name Mala-corhinus, a name which may come into general use when thespecies are better known. In the deep seas rays are foundeven under the equator. In the south-temperate zone thespecies are mostly generically distinct, Psammobatis being atypical form, differing from Raja. Discobatus sinensis, com-mon in China and Japan, is a shagreen-covered form, lookinglike a Rhinobatns. It is, however, a true ray, laying its eggsin egg-cases, and with the pectorals extending on the Rajidcc, known by the teeth and bony tubercles, arefound from the Cretaceous onward. They belong
Fishes . generic name Mala-corhinus, a name which may come into general use when thespecies are better known. In the deep seas rays are foundeven under the equator. In the south-temperate zone thespecies are mostly generically distinct, Psammobatis being atypical form, differing from Raja. Discobatus sinensis, com-mon in China and Japan, is a shagreen-covered form, lookinglike a Rhinobatns. It is, however, a true ray, laying its eggsin egg-cases, and with the pectorals extending on the Rajidcc, known by the teeth and bony tubercles, arefound from the Cretaceous onward. They belong to Raja andto the extinct genera Dynatobatis, Oncobatis, and genus Arthropterus (rileyi), from the Lias, known from alarge pectoral fin, with distinct cylindrical-jointed rays, mayhave been one of the Rajidcc, or perhaps the type of a distinctfamily, Arthropterida. Narcobatidae, or Torpedoes.—The torpedoes, or electric rays(Narcobatidcc), are characterized by the soft, perfectly smooth. Fio. 151.—Numbfish, Narcine hrnsihetisin Henlp, showing electric , Fla. skin, by the stout tail with rayed fins, and by the ovoviviparoushabit, the eggs being hatched internally. In all the species isdeveloped an elaborate electric organ, muscular in its originand composed of many hexagonal cells, each filled with softfluid. These cells are arranged under the skin about the liack The True Sharks 211 of the head and at the base of the pectoral fin, and are capableof benumbing an enemy by means of a severe electric exercise of this power soon exhausts the animal, and acertain amount of rest is essential to recovery. The torpedoes, also known as crampfishes or numbfishes,are peculiarly soft to the touch and rather limp, the substanceconsisting largely of watery or fatty tissues. They are foundin all warm seas. They are not often abundant, and as foodthey have not much value. Perhaps the largest species is Tetronarce occidentalis, thecrampfish of our A
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