SHARKS AND RAYS 



669 



SHOVEL-NOSED SKATE 



Knoiun also as the Ha/a^'i Ray 



i.u,lj., 



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-fisi 1 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 toa mere vestige, 

 as in the HORNED Ox-RAV, 

 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. 



li^^lV 



PJloIo by IV, Savilll-Kinl, f.Z.S.J 



PAINTED SKATE 



So called on account of tls conspicuous coloration 



