DORSAL VIBRATLLE FIX OF THE R,OOKLLVG (AIOTELLA). 24-3 
at rare intervals, cease for several seconds, or even a few 
minutes. This interval of cessation is irregular and non- 
periodic. When the movement is about to be discontinued, 
the posterior rays cease first, and then later, those situated 
more anteriorly. In a similar manner, when the movement is 
being resmned, the anterior rays come into motion previous to 
the posterior processes. 
In a good light the individual processes can be detected 
with the naked eye originating from a greyish ridge at the 
base of the groove, and with a reddish area on either side of 
the raised part. The atiterior ray has only a very slight 
vibration in a laternl direction, which may be observed with 
a lens. 'I’he movement of the other processes is in a latero- 
posterior direction. On firmly pressing the surface of the 
anterior })rocess with a sharp pencil or other small object it 
becomes depressed, and the movement of the remaining rays 
ceases, and conversely, on placing pressure on the small 
processes situated immediately posterior to the large ray, 
the latter is depressed. Tin's depression of the anterior ray 
also occurs with fairly firm contact on the posterior processes, 
but not in such a marked degree. When a thin strip of 
])aper is ])laced along the posterior surface of the large 
})rocess, the small raj’s cease their movement; this means of 
communication seems localised, for when the paper is placed in 
contact with the anterior side, the cessation of vibration does 
not take place. 'I’here is thus apparently a certain degree of 
continuity between the large anterior process and the smaller 
rays. The small rays or groups of those have, however, the 
power of independent movement, for on touching certain of 
them their movement ceases, while those situated anteriorly 
or posteriorly still have the power of vibrating. 
The result of coating the sides of the groove, in which the 
fin is situated, with black asphaltum, was a cessation of the 
movement of the vibrating rays for some time, although when 
the rockling was touched and consequently changed its 
position the rays recommenced to act ; but otherwise the 
fish appeared curiously inert, almost as if asleep. In half an 
