302 
CARTILAGINEI. — SQUALID^E. 
The teeth of the Sharks constitute a most 
formidable apparatus. They are generally tri- 
angular, very sharp-pointed, and often have a 
small point on each side the principal one ; they 
are flat, and the edges are keenly cutting, so that 
they resemble lancets ; moreover, in some cases, 
the edges themselves are notched into minute 
saw-like teeth. Each of these lancet-teeth alone, 
in a Shark of considerable size, would inflict a 
severe gash ; what then must be the effect of a 
whole mouthful of such weapons, above and 
below, arranged in serried order, rank behind 
rank, and moved with the force of powerful 
muscles ? The teeth of a fossil Shark are found 
two inches and a half in diameter, from base to 
point. 
The mode by which the race of these formidable 
creatures is continued, differing as it does so 
greatly from that of most other fishes, is exceed- 
ingly curious. The Shark, instead of depositing 
some millions of eggs in a season, like the Cod or 
the Herring, produces two eggs, of a square or 
oblong form, the coat of which is composed of a 
tough horny substance ; each corner is prolonged 
into a tendril, of which the two which are next 
the tail of the enclosed fish are stronger and more 
prehensile than the other pair. The use of these 
tendrils appears to be their entanglement among 
the stalks of sea-weeds, and the consequent 
mooring of the egg in a situation of protection 
and comparative security. Near the head there 
is a slit in the egg-skin, through which the 
water enters for respiration, and another at the 
opposite extremity by which it is discharged. 
That part of the skin which is near the head, is 
