586 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
The oesophagus is very narrow, and already bears a 
pair of little diverticula which ultimately form the thick 
walls of the pharynx. The stomach-—-which often 
contains the skeletal parts of unicellular organisms—is 
provided with a large dorsal lobe or caecum (Pl. I., fig. 
15, Caec.), and its walls are thickly packed with minute 
opaque granules which probably give them their deep 
violet colour. 
Metatrochophore.—The first metatrocho- 
phore stage closely resembles the trochophore, but is 
distinguished by the segmentation of the deeply-staining 
tissues of the ventral surface behind the prototroch. The 
larva is, moreover, larger and two pairs of more rounded 
eyes appear, one slightly antericr and the other slightly 
dorsal to the original crescentic pair. A very short row 
of 1504 cilia can often be detected along the dorsal side 
of each of the crescentic eyes in this and later stages; I 
have been unable to find these in the specimens of the 
trochophore stage. 
The Metatrochophore increases in size and becomes 
more pointed at the posterior end (PI. I., fig. 16) as it 
passes into its second phase. The peristomial cirri appear 
close together immediately behind the prototroch; a pair 
of anal styles appear at the posterior end; and between 
these, set very close together, the parapodia of seven 
chaetigerous segments develop. Hach of these shows 
from the very first recognisable rudiments of all parts of 
the fully formed appendage except the dorsal tuft of 
setae; whilst the elytra of segments 2, 4, 5, 7 (and later 
9, 11, 13, ete.) are more disc-like than the dorsal cirri of 
the other segments even at this early stage (Pl. L., 
fig. 16, Hl.). The pair of diverticula of the oesophagus 
have become much larger, and their walls much thicker 
than in the Trochophore. 
44) 
