682 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
ful (100) cilia appears a little behind the first, and 
shortly after this the region between the mouth and the 
anterior of these bands becomes marked out into segments 
by the appearance of successive rows of setae, the anterior 
setae of each row being short and the succeeding ones 
each a little longer than the one in front (Pl. IV., fig. 
13); in the oldest specimen seen too (1,150 by 900% in 
size when contracted), the special stout setae of the fourth 
chaetigerous segment are visible embedded in the body- 
wall. Between the second band of powerful cilia and the 
caudal appendage deeply-staining segments are formed. 
Whilst seementation is in progress the deeply-cleft under- 
lip grows more rapidly than the prostomium (compare 
Pl. IV., figs. 12 and 13) till in the oldest specimen seen 
(Pl. IV., fig. 14) the mouth is terminal, and being of 
enormous size occupies the whole of the anterior end of 
the body. In this specimen a pair of tentacles have 
begun to develop on the dorsal surface of the head, a short 
distance from its anterior margin. 
In specimens of these later stages, which were 
examined alive, the long rigid cilium, situated close to the 
anterior margin of the prostomium, between the anterior 
eyes, appeared to be feeling about in front of the animal 
as it moved along. One of these larvae, also, was seen to 
take into its mouth a good-sized copepod and swallow it ; 
whilst a Ceratium and a sponge-spicule entered the mouth 
of another, but were rejected. It was further noticed 
that the bands of powerful cilia were broken in the mid- 
ventral line and that a groove, apparently ciliated exactly 
like the general surface of the body, extended forwards 
from the anus towards the mouth through the gaps thus 
left. From Wilson’s account of the larvae of Chaetop- 
terus pergamentaceus (1882: pp. 285-6) it would appear 
that this is the case also in the early stage, when only the 
