1. Evidence is reviewed confirming that the eyes of Sepia move under the influence of gravity, angular acceleration and visual receptors.
2. Visual nystagmus and optomotor responses are described in free-swimming Sepia; these survive bilateral destruction of the statocysts, though they are abolished by blinding.
3. Post-rotatory nystagmus is shown by intact animals in a plain background; in bilaterally blinded animals there are post-rotatory movements of the head. These responses disappear if the statocysts are removed.
4. The post-rotatory nystagmus of intact animals is almost completely suppressed by visual cues.
5. Other effects of blinding and statocyst removal are described.