SHARKS AND RAYS 



271 



r 



^\ 



these its trivial name. All 

 these rays, in fact, have some 

 form or other of formidable 

 offensive and defensive appa- 

 ratus. The Sting-R.w 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 difi"erence 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. 



Finall}-, attention must be drawn to the remarkable transformation which the breast-fins 



r,,r,_^ and tail have undergone. The 



Phsla by W. Savillt-Kinl, f.Z.S.} 



SHOVEL-NOSED SKATE 



Krtoiun alio ai the Httlat'i Ray 



lMttJ,rd-in-Seit 



^m 





fhiii b, IV. Suvilli-Kini, F.Z.S.'j 



PAINTED SKATE 



So called on account of its conspicuous coloration 



\_Milfarii-on-iea 



former have developed into 

 powerful swimming-organs, 

 locomotion being eff'ected by 

 their undulatorj- movements, 

 instead of b}' 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-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. 



