SHARKS AND RAYS 
271 
these its trivial name. All 
these rays, in fact, have some 
form or other of formidable 
offensive and defensive appa- 
ratus. The Sting-ray has 
on its tail a fearful serrated 
dagger, 6 or 8 inches long in 
large examples ; while the 
Torpedo- or Numb-fish has 
electric organs in the head, 
with the aid of which it can 
give a shock sufficiently strong 
to paralyse the fishes on 
which it feeds. 
Two interesting peculi- 
arities of the rays deserve 
notice in concluding this 
chapter. The first is that 
their egg-purses, instead of 
attaching themselves with 
filaments to weeds and rocks, 
like those of the sharks, are 
provided with a sticky secretion which answers the same purpose of anchoring them in 
security from currents that would carry them out into deep, cold water. The second is 
the sexual difference in the teeth, which are pointed in the male and flat in the female. 
Whether this difference in the teeth (which may be likened to that between the bills of 
the male and female Huia-bird of New Zealand) indicates a corresponding difference in food, 
or, on the other hand, some co-operation between the sexes in procuring it, is an interesting 
question that our present slight knowledge of the habits of these fishes does not enable us 
to answer. 
Finally, attention must be drawn to the remarkable transformation which the breast-fins 
and tail have undergone. The 
former have developed into 
powerful swimming-organs, 
locomotion being effected by 
their undulatory movements, 
instead of by similar move- 
ments of the whole body, or 
by side-to-side motions of 
the tail, as in other fishes. 
Whilst the latter, no longer 
used in swimming, has either 
been reduced to a mere vestige, 
as in the Horned Ox-ray, 
or has become developed into 
a long and tapering “ whip- 
lash,” provided with a poison- 
spine. In such cases the long 
tail is used to encircle prey, 
and at the same time to force 
the victim on to the deadly 
spine. 
Photo by IV, SavilU-Kent.^ F.Z.S.] [^Milford-ori'^Sea 
PAINTED SKATE 
So called on account of its conspicuous coloration 
Vheie by fT'. SavilU~K«nt^ 
SHOVEL-NOSED SKATE 
Known also as the Halanii Ray 
\_Milford-on-Sea 
