622 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Polydora A (PI. II., figs. 28-30). The youngest 
specimen obtained is 580" long by 150 broad, and has 
nine segments. A short conical parapodial outgrowth is 
present immediately below each tuft of setae. The setae 
are smooth capillaries, those of the first seement being 
decidedly longer than the rest. The tentacles have not 
yet developed, which proves that this is not a later stage 
of the Polydora Metatrochophore described above. The 
head bears three pairs of eyes enmeshed in a reticulum 
of black pigment (as in Pl. IT., fig. 28, a later stage). 
Black pigment is present at the sides of the body, between 
the tufts of setae; on the third, fourth, and fifth seements 
a black band passes dorsally from each of these lateral 
patches, the anterior pair almost meeting in the middle 
line (as in Pl. II., fig. 28). On each of the remaining 
segments these bands are replaced by a median ramified 
patch; the posterior end of the anal segment is tipped with 
similar black pigment. No black pigment is present on the 
ventral surface. In a 12-segment larva the arrangement 
of the pigment is as before, but the ramified patches are 
much larger. A few provisional setae of the ventral tuft 
are beginning to project in addition to the dorsal ones on 
some of the anterior segments. It appears to be usual 
for the ventral provisional setae of Spioniform larvae to 
develop later than the dorsal ones, and to remain smaller 
than them (for other instances see Spronids A, C, D, 
above). 
The tentacles appear as a pair of short conical out- 
growths behind the prototroch (which does not extend 
along their bases) in a 17-segment stage. This 
larva is represented in fig. 29. It will be seen that the 
arrangement of the pigment remains very much as before. 
The fifth segment shows, embedded in the tissues, the. 
faintest rudiments of its specialised permanent setae, and 
