1. Savage, G. E., in The Central Nervous System and Fish Behaviour (edit. by Ingle, D. J.) (University of Chicago Press, 1968).
2. Savage, G. E., Nature, 218, 1168 (1968).
3. Hainsworth, F. R., Overmier, J. B., and Snowdon, C. T., J. Comp. Physiol. Psychol., 63, 111 (1967).
4. Aronson, L. R., in The Central Nervous System and Fish Behaviour (edit. by Ingle, D. J.) (University of Chicago Press, 1968).
5. Janzen, W., Zool. Jahrb. Abt. Allgem. Zool. Physiol., 52, 591 (1933).