Fic. 119.—Electric organ of the Skate. The left-hand drawing (I) represents the 
entire organ (natural size) of a fuli-grown RX. radzata. This is a small skate, which 
rarely exceeds 50 centms. in length; but in the large 2. dadzzs, the organ may 
exceed two feet in length. The other drawings represent single muscle-fibres in suc- 
cessive stages of transition. In the first of the series (II) the motor plate, and the nerves 
connected with it, have already been considerably enlarged. In the other three specimens, 
the fibre becomes more and more club-like, and eventually cup-like. These changes 
of shape are expressive of great changes of structure, as may be seen in the last 
of the series v), where the shallow cup is seen in partial section. The electric 
plate lines the concavity of the cup, and is richly supplied with nérves (only a few of 
which are represented in the last drawing): the thick walls of the cup are composed of 
muscular fibres, the striation of which is distinctly visible. 
* Rh 
