592, TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
troch, and is lined with cilia; these cilia are all curved 
inwards towards the oesophagus, and are not continuous 
with the longer cilia of the prototroch; they are, how- 
ever, continuous with a neurotroch, the cilia of which are 
only 104 long. ‘This neurotroch is in the form of a 
narrow median band, as in many other larvae, for the 
anterior third of its extent, but broadens out further back 
into a somewhat diamond-shaped tract, as shown in 
Pl. Il., fig. 6 (Wér.). The posterior angle of this tract is 
extended to the anus, which is closely surrounded by 
short cilia similar to those of the neurotroch. The true 
telotroch—though frequently, if not always, present—is 
also of very short cilia; it does not completely encircle 
the body, there being a ventral break in its continuity, 
the neurotroch extending through this without coming 
into contact with the telotroch. 
The preoral (ganglionic) and postoral (subsequently — 
segmented) deeply-staiming cell-masses are much less 
conspicuous in these Trochophores than in those of 
Polynoé, and are very much smaller in the earlier than 
in the later phases of this stage. 
Metatrochophore.—The first metatrocho- 
phore stage closely resembles the trochophore, but 
becomes somewhat larger, and the postoral deeply- 
staining cell masses are divided transversely into 
segments, of which the anterior are differentiated a little 
before the posterior. Although the segments thus appear 
in succession, it is possible to distinguish the seven that 
appear during the metatrochophore stage as primary 
segments, for their appendages reach an advanced state 
of development before any others are added. Very 
shortly after the appearance of segmentation, the 
appendages of these seven primary segments develop, and 
with this the second metatrochophore stage commences. 
fee A 
