The True Sharks 205 
The dorsals are small and far back, the tail is slender with 
small fins, all these being characters shared by the rays. But 
one genus is now extant, widely diffused in warm seas. The 
species if really distinct are all very close to the European 
Squatina squatina, This is a moderate-sized shark of sluggish 
habit feeding on crabs and shells, which it crushes with its 
small, pointed, nail-shaped teeth. Numerous fossil species of 
Squatina are found from the Triassic and Cretaceous, Sguatina 
alifera being the best known. 
Family Pristiophorida, or Sawsharks.— Another highly aber- 
rant family is that of the sawsharks, Pristiophoride. These are 
small sharks, much like the Dalatiid@ in appearance, but with the 
snout produced into a long flat blade, on either side of which is a 
Fig. 147. —Sawshark, Pristiophorus japonicus Gunther. Specimen from Nagasaki. 
row of rather small sharp enameled teeth. These teeth are smaller 
and sharper than in the sawfish (Pristis), and the whole animal 
is much smaller than its analogue among the rays. This saw 
must be an effective weapon among the schools of herring and 
anchovies on which the sawsharks feed. The true teeth are 
small, sharp, and close-set. The few species of sawsharks 
are marine, inhabiting the shores of eastern Asia and Aus- 
tralia. Pristiophorus japonicus is found rather sparsely along 
the shores of Japan. The vertebre in this group are also tecto- 
spondylous. Both the Squatina and Pristiophorus represent a 
perfect transition from the sharks and rays. We regard them 
as sharks only because the gill-openings are on the side, not 
