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vol-6BULLIDTIN OF THE INSTITlTTFJ OF OenA-NOGRAPH Y & FISHERIES 2] 7 .~–~._- ~~~-
SUMMARY
Fusus tuberculatus lays its brick-red eggs in adherent,
transparent, colourless, flattened vase-shaped capsules.
Each cap.mle contains an average of about 250 eggs (I80
to 200 M), of which only 3%develop into embryos and the
rest are nurse cells. The first two cleavages are nearly
equal. Tile development proceeds slowly, the gastrula
is reached after 6 days and the free swimming larva hatches after 30to 50 days ofspawuing. The veliger is provided with a four-lobed vdum (the two posterior Ones are
long~r than the anterior), a very powerful foot differentiating into a cylindrical propodium and flat metapodium with a protruding large operculum, and a dark
brown fusiform elongated shell of about two whorls
(I.5 mms. long and 1 mm. wide). The planktonic life
is short, and the creeping young is reached after two
days of swimming. The new growth of the shall consists
of parallel undulating ridges, and a complete new whorl
is form~d after 25 days of creeping.
