158 
ON THE ORGAN OF HEARING 
half turn outwards, and, mounting upwards, enters the an- 
terior cartilaginous canal, and is attached to the superior 
curve of the membranous tube. * 
The great sac and this elastic oblong substance are both 
attached to the parietes of the vestibule by long slender 
membranous fibres, which intersect the vestibule in various 
directions, but admit of slight elongation ; and, consequent- 
ly, when these bodies are affected by the agitation of the 
surrounding fluid, the membranous fibres will assist to con- 
troul and mitigate the effect of powerful or violent vibra- 
tions, and, at the same time, secure the sac in its natural 
position. 
As this fluid surrounds the membranous sac in the ves- 
tibule, and its ramifications in the canals, so it may from 
that circumstance be termed the Liquor Labyrinthi am- 
plectens ; and that which is contained in the sac and tubes, 
the Liquor Labyrinthi inclusus. 
The ear of the Skate bears a great resemblance to that 
of the Shark, so much so, that I have endeavoured to com- 
pare the one with the other whenever an opportunity oc« 
curred. The ampulls? and semicircular canals are as large 
in diameter, and the vestibule of greater magnitude, parti- 
cularly the superior parts of the cavity ; but the cartilagi- 
nous canals are shorter, and lie close to the vestibule ; 
and, indeed, great part of the membranous tubes is contained 
in that cavity, the cartilaginous canals being apparently of 
no other use than as so many loop-holes to keep the mem- 
branous tubes from intermingling with the sac ; and this 
gives them a seeming deficiency in length, and an appear- 
* The parts of this organ appear admirably adapted to the purposes 
for whicli thej seem intended. Thus, this organised reticulated mem- 
branous body in the adult, is composed of only a few delicate, and al- 
most invisible, membranous fibres in the young. 
