1. Packard, A., Biol. Rev., 47 241–307 (1972).
2. Ito, M., in The Nervous System, 1 (edit. by Tower, D. B.), (Raven, New York, 1975).
3. Collewijn, J., J. exp. Biol., 52, 369–384 (1970).
4. Fukada, J., Highstein, S. M., Ito, M., Expl Brain Res., 14, 511–526 (1972).
5. Maekawa, K., and Simpson, J. I., Brain Res., 39, 245–251 (1972).