32 LIVERPOOL BIOLOGICAL SOCIETY. 
muscular bands and the funiculus are attached. Round 
the mouth is a circlet of short blunt sets, which form the 
ctenostome. They close the aperture when the polypide 
is retracted. Smitt gives the number of sete as 14—15, 
but in some specimens I have counted more than twenty. 
Round the mouth in the inner side is a mass of cells, 
from which springs the tentacular sheath. This consists 
of muscular fibres arranged longitudinally and transversely. 
A very powerful sphincter muscle contracts the neck when 
the polypide is not expanded. Strong retractor muscles 
spring from the sheath where it joins the lophophore and 
run to the cell walls (parieto-vaginal muscles). (PI. III., 
fig. 3.) 
Looking down on the invaginated tentacular sheath, 
one sees a circular aperture, and the walls open out ina 
cone-like manner, the lower end being continuous with 
the lophophore. (PI. III., figs. 3 and 4.) 
Round the mouth, on the outer surface, is found in most 
specimens a cluster of long hair-like bodies, some resting 
on small raised papille. Their function would seem to be 
sensory, and they probably indicate the approach of danger 
or the proximity of food. In the living state they move 
about slowly when the polypide is retracted (PI. II1., fig. 3). 
The lophophore bears 15—17 tentacles, according to 
Hincks. In all those examined by myself the number has 
been sixteen. They are longer in one direction than the 
other, as pomted out by Dr. Farre (Phil. Trans., 1837). 
These notes only treat of a few points of structure, 
and many other details in this species require investigation. 
The embryology especially calls for further research, but 
as this can only be satisfactorily done with the animal in 
the living state, it is hoped that the Marine Biological 
Station at Puffin Island may afford opportunities of 
investigating the matter. 
