THE ELECTRIC EEL. 139 



FAMILY XXV. HALOSAUKID^;. 



This family has but one genus, the Halosaurus. Both body and head are covered with cycloid 

 scales ; the long body terminates in an exceedingly long tapering tail ; the snout projects far beyond 

 the mouth. There is only one and a half series of scales between the lateral line and the ventral 

 tin. Halosaurus oweni is found at Madeira. Other species range down to a depth of 2,750 fathoms. 



FAMILY XXVI.-GYMNOTID.E. 



This family includes a small assemblage of fishes having a long eel-shaped body, a long anal tin, no 

 ventral tin, and a tapering tail, the extremity of which is capable of being reproduced. 



The ribs are well developed, the air-bladder is double, and the vent is near to the throat. All 

 these fishes are confined to the fresh waters of the tropics, abounding in Brazil and the Guianas. Only 

 one member of the family the Electric Eel (Gymnotus electrlcus) possesses electric properties. It is 

 the only species which is entirely devoid of scales; it possesses a single row of conical teeth; the dorsal 

 and caudal tins are entirely absent, but the anal tin is prolonged to the end of the tail. 



The electric organ is placed on each side of the lower part of the tail, reaching forward to the vent, 

 and forming a third of the weight of the animal. The colour of the fish is blackish above, but the belly 

 is of a paler and reddish tinge. Ill-defined spots frequently extend along the back and sides. The length 

 varies from three to six or seven feet. The experience of observers has varied as to the effects of 

 the electric power of the fish, but it seems to be agreed that if it be picked up by the tail sensations of 

 an acute and painful character are felt and do not immediately pass away. It is well known that cats 

 and dogs perform remarkable feats of a gymnastic character after the incautious examination of this 

 animal. It is shunned by the other inhabitants of the river, and dreaded by the Indians, who, never- 

 theless, overcome their scruples when the animal is dead, for the muscles are accounted palatable, 

 though the flavour of the electric organ is unpleasant. 



The shock is said to be sufficiently powerful, in the case of large fishes, to paralyse horses and 

 kill small animals, and is much more severe than the shock from the torpedo. The discharge takes 

 place apparently under the action of the will. In South America wild horses have been driven into the 

 rivers by parties travelling, so that the fishes might exhaust their energies on the horses before the 

 men ventured in the water. The fish sometimes die from excessive exhaustion, but usually regain the 

 electric energy in a few hours. The two ends of the fish are in opposite electrical conditions, so that 

 the most powerful shock is received when contributed to by the head and tail of the fish. The electric 

 nerves are very numerous, and belong partly to the fifth pair, and partly to the intercostal series. 



The Electric Eel does not often eat the fishes killed by its shocks. 



The other genera in this family are all covered with scales. Sternarchus has the tail terminating 

 in a small caudal fin, and there is a rudimentary dorsal fin attached by a band of fat to a groove in the 

 back of the tail ; but in Rhamphichthys, Sternopygus, and Carapus the tail terminates in a free point. 

 Several species of the genera Sternarchus and Rhamphichthys have the snout produced into a more or 

 less long tube. 



FAMILY XXVII. SYMBRANCHID^. 



This is a small and varied group of Eel-like fishes, which have the body naked or only covered 

 with minute scales ; the upper jaw is entirely formed by the pre-maxillary bones, the maxillary bones 

 being placed behind them in a parallel position. 



There are no pectoral or ventral fins, and all the vertical fins are reduced to little more than 

 membranous folds. There is no air-bladder, and there are no pyloric appendages to the stomach. All 

 these fishes are found in tropical regions ; the first group, Amphipnoina, is formed for the Bengal species 

 Amphipnous cuchia. It has the vent in the posterior half of the fish's length, and is covered with 

 minute scales ; the palatine teeth are in a single series, and there is an air-sac communicating with 

 the gill-cavity. There are one hundred and six vertebrae in the abdomen and sixty-five in the tail. 

 It is found in Bengal. 



The second group, Symbranchina, includes the genera Symbranchus and Monopterus, both naked 

 fishes, and neither possesses the accessory breathing sac. Monopterus is from the East Indies 'and 

 Japan ; Symbranchus has a species in tropical America and another in the East Indian region. 

 The third group of the family, named from the typical genus, has but one species Chilobranchus 



