PT4 Introduction
Darwin, C.R., 1860, The Correspondence of Charles Darwin, Cambridge: Cambridge University Press, Vol. 8 Fernald, R. D., 1997, The evolution of eyes', Brain, Behaviour and Evolution, 50, 253-259 Goldsmith, T. H., 1990, 'Optimisation, constraint, and history in the evolution of eyes', The Quarterly Review of Biology, 65, 281-322 Provencio, I., et al., 1998, 'Melanopsin: An opsin in melanophores, brain and eye', Proceedings of the National Academy of Sciences USA, 95, 340-345 Wolken, J. J., 1995, Light Detectors, Photoreceptors, and Imaging Systems in Nature, Oxford: Oxford University Press
