DORSAL VIBRATIDE FIN OF THE ROCKLING (MOTELLA). 245 
gelatine and tannin, and even cut them away entirely, without 
apparently causing any physical discomfort, and without 
affecting’ the movements of the fish. He also states that 
cutting away the rays was subsequently followed by their 
regeneration. I obtained somewhat similar results so far as 
reo:ards the fin itself, but I hold that the author has neglected 
the study of the skin in the immediate proximity of the 
vibrating rays. 
In the course of my work I was early struck by the fact 
that the skin in the near neighbourhood of the vibrating 
231'ocesses is extremely sensitive ; thus, for example, when a 
thin strip of paper is laid on the sides or apex of the groove 
bordering the processed, the movement of the latter is brought 
to a standstill. On the other hand, if the same contact is 
tried on the dorsal and pectoral fins, or on the surface of the 
head, the movement of the rays continues uninterruptedly. 
I will have occasion later on to refer to the occurrence of a 
number of tactile nerve-endings on the skin of the groove in 
which the rays are situated. 
It is not easy to understand how Bogoljubsk_y arrived at 
his conclusion that neither from morphology nor from physio- 
logy can one ascribe any physiological role to this organ. 
'I'he vibratile fin of Motella, which may be termed the 
oi-al fin in contrast to the longer dorsal or aboral fin, is 
comparal)le in general structure to that of the unpaired dorsal 
fin of other Gadidae. 
In the case of the smaller processes the structure is as 
follows ; 
From the spinous process of the vertebra a ray-carrier 
or radial passes dorsalwards, and at the apex of the latter 
a small spheidcal articulating process is situated to which 
the ray is attached. The radials or ray-carriers have a 
pillar-like form, differentiated into three parts, namely, a 
head, neck and liase. The ray-carrier consists of hyalin 
cartilage which is richly impregnated with salts of lime. 
The individual ray-carriers are connected with one another 
by ligamentous tissue. 
