208 ZOOLOGY. / 



strong man to carry. The electric or galvanic apparatus consists of four 

 longitudinal bundles, disposed in two pairs, one larger above, and a smaller 

 below, against tde base of the anal fin. The fasciculi are divided by longi- 

 tudinal partitions into hexagonal prisms, and transverse divisions separate 

 these into small cells. The cells are filled with a gelatinous matter, and 

 the whole apparatus is abundantly supplied with nerves from the spinal 

 marrow. In the Torpedo, these nerves come directly from the brain. 



The amount of electricity furnished by the Gymnotus is enormous. 

 Faraday made a calculation in regard to a specimen of ordinary size 

 examined by him, that a single medium discharge was equal to that from a 

 battery of 3500 square inches charged to its maximum. It need not then 

 be a matter of surprise that the Gymnotus is capable of killing a horse by 

 repeated discharges ; which it does by applying its whole length along the 

 belly of the animal when in the water. The method of capturing the 

 Gymnotus made use of by the South American Indians, consists in driving 

 a number of horses and other cattle into the muddy pools in which the 

 electric eels abound. Roused from their retreats in the mud, the Gymnoti 

 emerge into the water, and gliding in among the animals, give to them 

 violent shocks. A succession of discharges I'esults in weakening the eels 

 to such a degree, as to make it a matter of little danger or difficulty to 

 capture them. The Voltaic pile, formed by the electric apparatus of the 

 Gymnotus, is much like that of the Torpedo ; the column being longitudinal, 

 however, in the natural position of the animal, instead of vertical. The 

 anterior or cephalic extremity is positive; the caudal negative; and the 

 animal is capable of discharging any portion of its column. The substance 

 occupying the cells is a dense albuminous liquid, with a small amount of 

 common salt. Each cell is separate and independent, answering to the 

 cell of the galvanic battery. This electrical power is not confined to the 

 Gymnotus. Various species of Torpedo, one of which is found on the 

 coast of Massachusetts, exhibit the same property in a high degree. Other 

 electrical fishes are Malapterurus electricus, Trickiurus electricus, andTe^ra- 

 odon electricus. Some insects, too, as Redivivus se7-rahis and Mantis 

 electricus, are reported to give electric shocks. It may be proper to men- 

 tion, in conclusion, that the electricity of the Torpedo and Gymnotus is 

 capable of exhibiting all the effects of ordinary electricity, and is in most 

 cases entirely at the command of the animal, whether to emit or withhold it, 



Clupeid^. The fishes of this family exhibit considerable analogies to 

 the Sahnonoids, differing, however, in the absence of an adipose dorsal. 

 Both maxillaries and intermaxillaries are employed in forming the margin 

 of the upper jaw, instead of the usual introduction of the latter alone. The 

 body is well scaled, the scales sometimes very large. Bones of the mouth 

 variously provided with teeth, these occurring sometimes on the pectinated 

 tongue. 



The fishes of this family are among the most useful and indispensable to 



man. It includes the anchovy, the sardine, the sprat, the various herrings, 



and the shad. The Anchovy, Engraulis encrasicholus {pi. 81, fig. 3), is a 



small fish, a few inches in length, distributed throughout Europe, and 



412 



