TORPEDO RAY. 300 



semicircular cartilages of each great fin, and ex- 

 tending longitudinally from the anterior extremity 

 of the animal to the transverse cartilage which 

 divides the thorax from the abdomen ; and within 

 these limits they occupy the whole space between 

 the skin of the upper and of the under surface : 

 ' they are thickest at the edges, near the centre of 

 the fish, and become gradually thinner towards 

 the extremities. Each electric organ, at its inner 

 longitudinal edge, is a convex elliptic curve. The 

 anterior extremity of each organ makes the section 

 of a small circle 3 and the posterior extremity makes 

 nearly a right angle with the inner edge. Each 

 organ is attached to the surrounding parts by a 

 close cellular membrane, and also by short and 

 strong tendinous fibres, which pass directly across, 

 from its outer edge, to the semicircular cartilages. 

 They are covered above and below by the common 

 skin of the animal ; under which there is a thin fascia 

 spread over the whole organ. This is composed of 

 fibres, which run longitudinally, or in the direction 

 of the body of the animal : these fibres appear to 

 be perforated in innumerable places ; which gives 

 the fascia the appearance of being fasciculated : its 

 edges, all round, are closely connected to the skin, 

 and at last appear to be lost, or to degenerate into 

 the common cellular membrane of the skin. Im- 

 mediately under this is another membrane, exactly 

 of the same kind, the fibres of which in some mea- 

 * sure decussate those of the former, passing from 

 the middle line of the body outwards arid back- 

 wards. The inner edge of this is lost with the first 



