Fishes . The True Sharks 20c The dorsals are small and far hack, the tail is slender withsmall fins, all these being characters shared by the rays. Butone genus is now extant, widely diffused in warm seas. Thespecies if really distinct are all very close to the EuropeanSqiiatina squaiina This is a moderate-sized shark of sluggishhabit feeding on crabs and shells, which it crushes with itssmall, pointed, nail-shaped teeth. Numerous fossil species ofSqiiatiiia are found from the Triassic and Cretaceous, Squaiinaalifera being the best known. Family Pristiophoridae, or Sawsharks. — Another highly
Fishes . The True Sharks 20c The dorsals are small and far hack, the tail is slender withsmall fins, all these being characters shared by the rays. Butone genus is now extant, widely diffused in warm seas. Thespecies if really distinct are all very close to the EuropeanSqiiatina squaiina This is a moderate-sized shark of sluggishhabit feeding on crabs and shells, which it crushes with itssmall, pointed, nail-shaped teeth. Numerous fossil species ofSqiiatiiia are found from the Triassic and Cretaceous, Squaiinaalifera being the best known. Family Pristiophoridae, or Sawsharks. — Another highly aber-rant family is that of the sawsharks, PristiophoridcB. These aresmall sharks, much like the Dalatiidcc in appearance, but with thesnout produced into a long fiat blade, on either side of which is a. Fig. 147 —, PristiophorusjaponicusGxxnthcT. Specimen from Nagasaki. row of rather small sharp enameled teeth. These teeth are smallerand sharper than in the sawfish (Pristis), and the whole animalis much smaller than its analogue among the rays. This sawmust be an effective weapon among the schools of herring andanchovies on which the sawsharks feed. The true teeth aresmall, sharp, and close-set. The few species of .sawsharksare marine, inhabiting the shores of eastern Asia and Aus-tralia. Pristiophoriis japonicus is found rather sparsely alongthe shores of Japan. The vertebrae in this group are also tecto-spondylous. Both the Sqiiatina and Pristiophoriis represent aperfect transition from the sharks and rays. We regard themas sharks only because the gill-openings are on the side, not 2o6 The True Sharks crowded downward to the under side of the body-disk. Asfossil, Pristiophoriis is known only from a few detached verte-brae found in Germany. Suborder Batoidei, or Rays.—
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