Figure 1.

Transverse sections through the mid-oesophagus (oe) of gastropod larvae. (a) Conus lividus larva 42 days after hatching showing the presumptive venom gland (asterisk) as enlarged cells extending down the ventral wall of the mid-oesophagus. (b) Conus lividus larva at or near metamorphic competence (49 days after hatching) showing further enlargement of presumptive venom gland cells (asterisk); boxed area enlarged in inset. Inset, detail of venom gland cells showing many small granules. (c) Marsenina stearnsii larva at or near metamorphic competence showing the ventral zone of enlarged cells (asterisk) that will become the mid-oesophageal gland at metamorphosis. Scale bars: (a) 20 µm; (b) 20 µm (inset 10 µm); (c) 20 µm.