556 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
composed of two longitudinal rows of columnar ciliated 
cells. 
The cavity of the vesicle is filled by a clear trans- 
parent fluid. Fitting on the pad internally is a small 
conical calcareous statolith (fig. 67a, and 67, /Stat.), 
which is probably secreted by the cells of the pad. 
The function of the statocyst is that of equilibration. 
Experiments in cther Cephalopods have shown that 
destruction of one or both statocysts causes loss of power 
to balance properly in the water. The description given 
by Owsjannikow and Kowalevsky of the statocyst of 
Octopus agrees with this organ in Hledone. Kolliker has 
shown that the short blind finger-hke canal, running 
outwards from the wall of the vesicle near the 
sensory ridge (fig. 67, A.C.), is the ciliated remnant of 
the invagination which gives rise to the auditory pit, seen 
in the embryos of Cephalopods. 
REPRODUCTIVE SYSTEM. 
I. FEMALE: 
The Ovary occupies the posterior end of the visceral 
dome. It is a large organ, the size varying with the 
season, and with the maturity of the specimen. When 
enlarged, the ovary pushes the kidneys which before 
partially overlaid it forwards and to one side, thus 
separating them posteriorly (PI. V, fig. 37, G. and #. K.). 
The gonad is a whitish oval gland, with a thick tough 
wall. The ventral region of this wall alone bears the ova, 
which are suspended from it in racemes. Hence the 
germinal epithelium of the ovary is confined to this 
ventral region. ‘here are from 30 to 40 racemes of ova 
(Pl. V, fig. 39, ov.). Elsewhere the wall of the ovary is 
smooth, with the exception of a much folded and twisted 
