THE GYMNOTID EELS OF TROPICAL AMERICA. 161 
II. Trunk Musculature. 
The disposition of the muscles in the trunk is much the same for all species of 
the Gymnotide, 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 interhemal 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 GYMNOTIDA. 
I. Electrophorus electricus (Linnzeus). 
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 cireum- 
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 like 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 Torporifie Kel is 
