SERPENTS. 
749 
account of its properties. Mess. Adaiison and Forskal make, a short 
mention of it, and M. Broussonnet describes it under the French name 
of Le Trembleur, in the Hist, de V Academic Royal des Sciences, for the 
year 1782. This animal belongs to the order called, in Willoughby’s 
system, silurus: hence it is commonly called silurus electricus. Some 
of these fishes have been seen even above twenty inches long. The 
body of the silurus electricus is oblong, smooth, and without scales ; 
being rather large, and flattened towards its anterior parts. The 
eyes are of a middle size, and covered by the skin which envelops 
the whole head. Each jaw is armed with a great number of small 
teeth. About the mouth it has six filamentous appendices, viz. 
four from the under lip, and two from the upper ; the two external 
ones, or farthermost from the mouth on the upper lip, are the longest. 
The colour of the body is grayish, and towards the tail it has some 
blackish spots. The electric organ seems to be towards the tail, 
w'here the skin is thicker than on the rest of the body ; and a whitish 
fibrous substance, which is probably the electric organ, has been 
distinguished under it. It is said that the silurus electricus has 
the property of giving a shock, or benumbing sensation, like the tor- 
pedo, and that this shock is communicated through substances that 
are conductors of electricity. 
A fourth electrical fish was discovered on the coast of Joanna, the 
chief of the Comoro islands, in lat. 12° 13' S. by lieutenant William 
Paterson. An imperfect account of it was published in the Phil. 
Trans, vol. 76. This fish is described to be seven inches long, and 
two and a half inches broad ; it has a long projecting mouth, and 
seems of the genus Tetrodon. The back of the fish is of a dark brown 
colour, the belly part of sea-green, the sides yellow, and the fins and 
tail of a sandy green. The body is interspersed with red, green, and 
white spots, the whjte one particularly bright ; the eyej^ large, the 
iris red, its outer edge tinged with yellow.” Mr. Cavallo adds to 
this description, that, while this fish is living, strong^^lectrical shocks 
are felt by a person who attempts to hold it between his hands. Three 
persons are mentioned, in the account, to have experienced this pro- 
perty of one of these fishes ; but the’ want of opportunity prevented 
further experiments.” 
Besides those animals which manifest their electric power evidently 
by giving a strong shock, there are others in which the fluid seenis 
to act by the emission of light. This indeed has not been proved by 
actual experiment, though it would certainly be well worth while to try 
whether by insulating a number of them, any more evident signs of 
electricity could be obtained. These creatures are of the insect tribe • 
some of them furnished with wings, as the shining flies in the warm 
countries; whilst others, as the glow-worm, crawl perpetually on 
the earth. It is most probable also, that the sparkling of sea-water 
is owing to the electricity of the insects in it. 
Tricks performed with Serpents. 
Casaubon says, that he knew a man who could at any time 
summon one hundred serpents together, and draw them into the 
