636 TRANSACTIONS, LIVERPOOL BLOLOGICAL SOCLE'LY. 
little spherical projection (Pl. IV., fig. 47; Sph.) situated 
between the arms of the horseshoe-shaped anal ridge 
(An. R.), and immediately in front of this projection is a 
tuft of 20m cilia (7'.C. Nér.) from which a neurotroch 
(Ntr.) of 8 cilia extends forwards, to end a little behind 
the mouth in a short transverse row of 10 cilia (PI. IV., 
fig. 47c; C. trans.). The telotroch is situated anterior to 
the posterior end of the neurotroch. The larva grows 
considerably both in length and in breadth, and food 
material from the exterior may be found in the stomach. 
When the lips are contracted, larvae of the age of that 
shown in Pl. IV., fig. 41, are about 450 long by 3004 
maximum breadth. The paleae, or large setae that 
project forwards from the anterior end of the adult, may 
be seen developing in the dorsal body-wall on each side of 
these larvae, with their pointed distal extremities close 
behind the preoral band and their bases several segments 
further back. The horseshoe-shaped ridge on the posterior 
surface of the anal segment is considerably enlarged; as 
before it is covered with pigment spots. 
Metatrochophore II—The setae usually 
appear at about the period of development of the larva 
seen in Pl. IV., fig. 41, though one larva with fewer 
segments than this has setae which have already attained 
their full length for the larva! period (80%). The body 
next becomes more elcngated; the setae all attain thei 
full (larval) size; and a definite region appears between 
the last of the chaetigerous segments and the anal segment 
(Pl. IV., figs. 42 and 43b). This region bears no pigment 
spots, and shows a very short anterior part, consisting of 
one segment like those anterior to it, except for the 
absence of pigment and setae, and a longer (100s) 
posterior part—the rudiment of the scapha—which 
already shows traces of lateral processes in the specimen 
