ON THE ANASPIDACEA, LIVING AND FOSSIL. 903 
that the club-shaped rods are fixed into hollow sockets by 
means of a pedicel which is continuous into one of the columnar 
cells which form the outer wall of the otocyst. From these 
cells muscular strands pass outwards and are connected with 
the pigmented ectodermal cells upon the outermost wall of 
the antenna. The internal chitinous wall of the otocyst 1s 
furnished with short tooth-like sete. Below these setz are 
flattened cells which come into connection with fine nervous 
processes sent out from the nerve of the first antenna. 
TEXT-FIG. 6. 
Anaspides tasmaniz. Second antenna. 
The way in which this otocyst functions is not very 
obvious. It is clear that the club-shaped rods are not the 
final sense elements since they are not connected directly 
with the nerve-endings. ‘he final sense elements are 
evidently represented by the short setz on the internal wall, 
which have not been hitherto observed. It appears, there- 
fore, that the club-shaped rods transmit the stimulus through 
the fluid of the sac to the sensory sete on the internal wall 
and so to the nerve. The muscular apparatus connecting 
the club-shaped rods with the external ectoderm suggests 
that the original stimulus comes from the exterior, and 
VOL. 53, PART 3.—NEW SERIES. B15) 
