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cartilaginous, it is presumed the animals will continue to grow 

 during the whole period of their lives. 



This species is found in all the European seas, but espe- 

 cially in the North Sea. Like the other rays, it is very vora- 

 cious, feeding on small fish and crustaceous animals. 



The R. batis of Linnaeus, is found in almost all seas, but 

 seems to change places with the seasons. These appear to 

 be the most numerous of all the large fishes, owing perhaps 

 to the difficulty other large predaceous fish find in taking 

 so wide a mouthful, and to the spines with which their 

 bodies are armed. In accordance with the conjecture that 

 cartilaginous fish continue to grow so long as they live, 

 individuals are occasionallv taken of enormous dimensions. 

 They have been taken off our own coast of 200 weight, but 

 in the West Indies one was caught measuring thirteen feet 

 in breadth, and twenty-five in length. The tail, however, 

 contributed largely to those prodigious dimensions, as it was 

 fifteen feet long. That monsters of this size are not more 

 commonly found, is not perhaps so surprising, when we con- 

 sider that the smallest only approach the shore, and that the 

 larger individuals continue at all times prowling at the bottom 

 of the unfathomable depths of the ocean, where they may 

 continue to live and grow for a period quite unknown to us. 



They generally frequent those parts of the sea where the 

 bottom is muddy, feeding on every animal to be found, either 

 buried in the mud, or moving near its surface. 



Generation in the Kays is effected by actual copulation, 

 and the male is provided with two appendices, by means of 

 which he holds himself in contact with the female. They are 

 ovoviviparous, but their eggs are very curious, and to be com- 

 pared only to those of the sharks ; they resemble the husk, or 

 shell of certain vegetable seeds, as the pea, are composed of 

 two solid semitransparent tough square membranes, terminated 

 at each angle by a short appendix, but without the curling 



