THE TORPEDO, 
147 
Our native species, found mostly in winter, especially on 
the low sandy shores of Cape Cod is Torpedo occidentalism 
Its batteries and nerves are substantially as in the Euro- 
pean species. The electrical organs arc constructed on the 
principle of a Voltaic pile, consisting of two series or layers 
Fig. 189.— i?aja eglanteria, male. Mouth and gill-slits, jaws and teeth of Mylio- 
batis fremenvillii 
of six-sided cells, the space between the numerous fine 
transverse plates in the cells filled with a trembling jelly- 
like mass, each cell representing, so to speak, a Leyden jar. 
There are about 470 cells in each battery, each provided 
with nerves sent off from the fifth and eighth pairs of 
nerves. The dorsal side of the apparatus is positively elec- 
trical, the ventral side negatively so. The electri(;al cur- 
rent passes from the dorsal to the ventral side. When the 
