THE GYMNOTID EELS OF TROPICAL AMERICA. 161 



III. Trunk Musculature. 



The disposition of the muscles in the trunk is much the same for all species of 

 the Gynmotidw, although the individual muscles vary in size and shape with the 

 presence or absence of the pseudo-electric organs. The trunk muscles are all 

 paired, one on each side of the median line. Naming them in order dorsoventrally 

 they are, notalis externalis, notalis internalis, dorsalis, lateralis superior, lateralis 

 inferior, ventralis, and lateralis imus. The nomenclature of Fritsch is followed as 

 far as given, notalis is a new name. (See Plate XIX, figures 19, 20, 21, 22, 23.) 

 The region near the dorsal end of the interhcemal spine, which is not occupied by 

 other tissue, is filled with fat cells and connective tissue. On Plate XIX, fig. 20, 

 the pseudo-electric organs are to be noted. 



Electric Organs of the Gymnotid^e. 

 I. Electrophorus eledricus (Linnaeus). 



The electric eel is the only species of this group which has been demonstrated 

 to possess electric power. Richter in 1729 published the first scientific account of 

 this species in the Paris Academy. His account was soon followed by many 

 others. The earliest English description of this fish is that of Edward Bancroft 

 in his "Natural History of Guiana," 1769. This contains an interesting account, 

 which is here quoted: 



"There is one, however, of the Eel tribe which deserves particular attention, 

 and which I shall beg leave to call the Torporific Eel, till it is distinguished by a 

 more proper name. 



"This fish is a native of fresh water and is most commonly found in the River 

 Essequibo, being usually about three feet in length, and twelve inches in circum- 

 ference near the middle. It is covered with a smooth skin of a bluish lead color, 

 very much like that of sheet lead which has been long exposed to the weather, 

 being entirely destitute of scales. The head equals in size the largest part of the 

 body, but is somewhat flat on the upper and lower sides, and its upper surface is 

 perforated with several holes, like those of a Lamprey Eel. The upper and lower 

 jaws extend in equal distance, terminating in a semi-oar-shape, and forming a 

 wide mouth without teeth. On the back part of the head are two small fins, one 

 on each side, much hke the ears of a horse, are either elevated or depressed as 

 the fish is pleased or displeased. From about eight inches below the head, the 

 body gradually diminishes in size to the tail, which ends in a point, without a fin. 

 Under the belly is a fleshy fin, about half an inch in thickness and near three inches 

 wide, extending from the head to the point of the tail, but diminishing in width as 

 the body diminishes in size; this, with the two fins on the head are all that I found 

 on the body of this eel, which would be nearly round if deprived of the belly fin. 

 This fish frequently respires and elevates his head above the surface of the water 

 every four or five minutes. But the most curious property of the Torporific Eel is 



