POLYCHAT LARVA. 625 
in the posterior segments, where, in addition, a row of 
irregular black patches is present in front of each. 
The only other known Polydora-larva whose 
pigmentation is at all like this is figured by Hacker 
(1898: Pl. II., fig. 16). Three pairs of eye-spots are 
present, the inner- and outermost pair being larger than 
the middle pair; a small reticulate patch of pigment is 
present beside each eye of the outermost pair, but this 
does not extend amongst the eyes as in Polydora A. The 
ventral surface is free from this black pigment. 
Apparently no specimen obtained is old enough to bear 
erotchets; the stout setae of the specially modified fifth 
segment are, however, very evident, although the larvae 
have only 17 segments, at which stage this segment is 
almost unmodified in species A; capillary setae are still 
present on this segment. The specialised setae are very 
hike those of species A. One larva of species B was 
examined alive; the cilia are arranged as in species A. 
Claparede, as above mentioned, has described the 
development of larvae which he believed to be those of 
Leucodora, Justn. (=Polydora, Bose.) ciliata. Agassiz 
(1867 : pp. 242-3) disputes the identity of these larvae with 
this or any other species of the genus Polydora on account 
of the complete absenc2 of the special modifications of the 
fifth segment, even in the oldest larvae; and he goes on 
to describe the development of a species of Polydora— 
probably, he thinks, P. ciliata—from an 11-segment 
fomme(locs cit., Pl V.> fic. 26), in which “the fifth ring 
is much wider than any other, and has only three short, 
stout bristles on each side” (loc. cit., p. 244). Agassiz’s 
main contention, however, falls to the ground in view 
of the fact that Claparede’s oldest larva possessed only 17 
segments, at which stage, as noted above, it is only after 
a careful examination with a high power, of a transparent 
