FISHES. 
15 
HEAD OF HAMMER-SHARK. 
the figure of the head bearing no small re- 
semblance to that of the 
hammer used in caulking 
ships. 
Besides the senses which 
we have enumerated^ which 
Fishes possess in common 
with other Vertebrata^ 
there is another faculty 
with which some species 
are endowed^ quite peculiar 
to this Class. It is the power 
of communicating electric 
shocks at will to other 
creatures. The Fishes most 
noted for this property 
are the Torpedo^ occasionally found on our own 
shores, and the Gymnotus^ or Electric Eel, of 
South America, The electric organs consist of 
numerous six-sided cells, at first sight apparently 
composed of a clear trembling jelly, but really 
containing a great number of delicate membran- 
ous plates, separated from each other by a glairy 
fluid. In the Torpedo the prisms are placed ver- 
tically, and form two masses, one on each side of 
the head ; in the Gymnotus, they are horizontal, 
and form four such organs, one pair on each side 
of the body. 
The effects of fear in changing the colour of 
the human hair are well authenticated ; from the 
statement of a writer in the New Sporting Maga- 
zine,” it would appear that Fishes may be subject 
to similar phenomena, Into a pool of about 
four acres, partially surrounded with trees and 
terminating a range of other pools above, through 
