No. 5 (192 1) MADRAS AQUARIUM 63 



we usually call dogfishes, are chequered and striped. One, the 

 Tiger Shark {Stcgostoiiiitin tigri)iiini), sometimes attaining a length 

 of 15 feet, is striped with vertical bands of black in a wonderful 

 way when young. He is the most brightly coloured of his tribe. 

 The curious Hammerhcaded Shark (Tarn. Koiubaii surd) is common 

 in these seas ; young specimens are often entangled in drift nets 

 and sometimes we are able to exhibit one in this tank. The reason 

 of the name is obvious; each side of the head is prolonged 

 laterally into a great rectangular projection, the eye being carried 

 out with it. Large individuals are sometimes caught up to seven 

 feet in length : these are accounted savage and are black-listed as 

 man-eaters. 



The Rays {Thinikkai) live on the bottom resting there upon their 

 wide disc-shaped body ; the upper surface is usually sandy coloured 

 in life, so that as long as they remain quiet they are difficult to 

 distinguish. Certain species have bright blue spots scattered over 

 the back and others have various markings and marblings which 

 probably are mimetic, that is, they harmonize with the colour 

 of the bottom frequented by these particular species; a pebbly 

 bottom or one marked by scattered clumps of low weeds and shells 

 is imitated readily by fish with a tendency to brownish and whitish 

 marbling. Among the most peculiar of the ray family are the 

 Electric Rays {Ncircinc indica and TV. bniimca). They get their 

 popular name from the electric shock given out when touched. 

 With an adult ray, the shock is so strong as to paralyse the hand 

 and arm for the time being. Little ones of 6 or 8 inches in length, 

 usually shown in one of the table aquaria, give out merely pleasurable 

 thrills such as children love when handling toy electric 

 batteries. 



Nearly all the rays have long tails. Many have them whip- 

 like in length and tenuity ; these are often sold as curiosities by 

 fishermen. Most of these whip tails are armed with one and some- 

 times two bony spines often a foot or more in length, closely barbed 

 on either edge with cruel, backwardly-directed teeth. The wound 

 inflicted by these formidable weapons is greatly dreaded by 

 fishermen the world over ; the hurt, besides being deep and severe, 

 often festers and heals slowly. In some species actual poison 

 appears to be secreted in a gland at the base of the spine. 



The Eel family is represented in this tank by a true eel of a 

 species very closely related to the common European species 



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