FISH AS FA THERS, 169 



egg-cases closely resemble the common wrack to which 

 they are oftenest fastened ; and as they wave up and 

 down in the water with the dark mass around them, they 

 must be almost indistinguishable from the wrack itself 

 by the keenest-sighted of their enemies. This protective 

 resemblance, coupled with the toughness and slipperiness 

 of their leathery envelope or egg-shell, renders them 

 almost perfectly secure from all evil-minded intruders. 

 As a consequence, the dog-fish lay but very few eggs each 

 season, and those few, large and well provided with 

 nutriment for their spotted offspring. It is these purses, 

 and those of the thornback and the edible skate, that 

 we oftenest pick up on the English coast. The larger 

 oceanic sharks are mostly viviparous. 



In some few cases, indeed, among the shark and ray 

 family, the mechanism for protection goes a step or two 

 further than in these simple kinds. That well-known 

 frequenter of Australian harbours, the Port Jackson 

 shark, lays a pear-shaped egg, with a sort of spiral stair- 

 case of leathery ridges winding round it outside, Chinese 

 padoga wise, so that even if you bite it ( I speak in the 

 person of a predaceous fish) it eludes your teeth, and goes 

 dodging off screw-fashion into the water beyond. There's 

 no getting at this evasive body anywhere ; when you 

 think you have it, it wriggles away sideways, and refuses 

 to give any hold for jaws or palate. In fact, a more 

 slippery or guileful egg was never yet devised by nature's 

 unconscious ingenuity. Then, again, the Antarctic 

 chimaera (so called from its very unprepossessing personal 

 appearance) relies rather upon pure deception than upon 

 mechanical means for the security of its eggs. The shell 



