EAGLE-RAYS. 543 



represented by several genera, ranging over the Mediterranean, Atlantic, and Indian 

 Ocean, into the distinctive features of which it will be unnecessary to enter here. 

 A well-known example of the typical genus is the marbled electric ray (Torpedo 

 marmorata), represented in the lower figure of our illustration. The hexagonal 

 prisms forming the electric organs are subdivided into a series of cells by a number 

 of delicate transverse partitions ; the cells at the two ends of the prisms being 

 in contact with the skin, and the whole structure liberally supplied with nerves. 

 Internally each cell is lined by a nucleated structure, within which is a mass of jelly- 

 like substance. "The fish," writes Dr. Gtinther, "gives the electric shock voluntarily, 

 when it is excited to do so in self-defence, or intends to stun or kill its prey; but to 

 receive the shock the object must complete the galvanic circuit by communicating 

 with the fish at two distinct points, either directly, or through the medium of 

 some conducting body. If an insulated frog's leg touches the fish, by the end of 

 the nerve only, no muscular contractions ensue on the discharge of the battery, 

 but a second point of contact immediately produces them. It is said that a painful 

 sensation may be produced by a discharge conveyed through the medium of a 

 stream of water. The electric currents created in these fishes exercise all the other 

 known properties of electricity ; they render the needle magnetic, decompose 

 chemical compounds, and emit the spark." Specimens measuring from 2 to 3 feet 

 across the disc are stated to be able to disable a man by the discharge of the 

 battery. A writer in Land and Water, for 1869, in reply to Buckland, observes 

 that " I have taken two torpedos in the estuary of the Tees. You say the one you 

 dissected had nothing in its stomach. I was curious enough to see what those I 

 caught were living upon, so I put my knife into one, and took from him an eel 

 2 Ibs. in weight, and a flounder nearly 1 Ib. The next one I opened also, and was 

 astonished to find in him a salmon between 4 and 5 Ibs. weight ; and what I was 

 more astonished at was that none of the fish had a blemish of any description, 

 showing that your idea of the fish killing his prey with his electrical force is 

 quite correct." 



THE EAGLE-RAYS, Family MYLIOBATID^Z. 



Known also by the ill-sounding title of devil-fishes, the eagle-rays include the 

 largest representatives of their tribe, and are characterised by the extreme width 

 of the disc, owing to the great development of the pectoral fins, which are, however, 

 interrupted at the sides of the head, to reappear as one or two small cephalic fins 

 on the muzzle. The tail is slender and whip-like, the cleft of the mouth straight, 

 and the teeth, when present, take the form of a solid pavement, adapted for 

 crushing the shells of molluscs, and other hard substances. The eagle-rays are 

 inhabitants of tropical and temperate seas ; and the members of some of the genera 

 are remarkable for the development of the so-called cephalic fins into a pair of 

 horn-like appendages, which are stated to be employed in capturing the prey and 

 helping to convey it to the mouth. Five genera are included in the family, all 

 the members of which appear to be viviparous. 



The typical genus is represented by a small number of existing 

 Typical Genus. L . ?. , ^ p xi TIT T i *- ; 



species, two of which are European ; one of these, Myhobatis aqmla, 



