THE EAGLE RAYS 2919 



the muzzle; while the median fins are well developed. The family is 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 marmor- 

 ata), 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 deli- 

 cate 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 sub- 

 stance. "The fish," writes Dr. Giinther, "gives the electric shock voluntarily, 

 when it is excited to do so in self-defense, 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 sensa- 

 tion 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 com- 

 pounds, and emit the spark. ' ' Specimens measuring from two to three 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 two pounds in 

 weight, and a flounder nearly one pound. The next one I opened also, and was 

 astonished to find in him a salmon between four and five pounds weight; and 

 what I was more astonished at was that none of the fish had a blemish of any de- 

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

 is quite correct. ' ' 



THE EAGLE RAYS Family MTLIOBATID^S 



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

 largest representatives of their tribe, and are characterized 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 mollusks, 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 append- 

 ages, 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. 



