Fisher, R. A. 1930. The genetical theory of natural selection. Clarendon Press, Oxford. Futuyma, D. J. 1979. Evolutionary biology. Sinauer Associates, Sunderland, Mass. Hamilton, W. D. 1971. Geometry for the selfish herd. J. Theor. Biol. 31: 295-311. Harvey, P. H., Bull, J. J. and Paxton, R. J. Looks pretty nasty. New Sci. (in press). Pianka, E. R. 1978. Evolutionary ecology. 2nd ed. Harper and Row, New York. Rothschild, M. 1971. Speculations about mimicry with Henry Ford. In: Creed, R. (ed.), Ecological genetics and evolution. Blackwell, Oxford, pp. 202-223. 1972. Secondary plant substances and warning coloration in insects. In: van Emden, H. F. (ed.), Insect/plant relationships. Blackwell, Oxford, pp. 59-83. 1975. Remarks on carotenoids in the evolution of signals. In: Gilbert, L. E. and Raven, P. H. (eds.), Coevolution of animals and plants. Univ. of Texas Press, Austin, pp. 20-52. Wilson, E. 0. 1975. Sociobiology: the new synthesis. Belknap Press of Harvard Univ. Press, Cambridge, Mass.