This book has concentrated on the nine most commonly used laboratory animals. Yet as illustratedin Table 11.1, many other species are used in biomedical research and toxicological assessment that have not been discussed. For example, the chicken is acommon model for organophosphate insecticide-induced neurotoxicity (Murphy, 1986), but we have made no mention of the chicken in this book (nor will we again). See Chapter 16 for amore complete discussion on animal model selection.