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An estimate of the number of species, S , usually called species richness by ecologists, in an area is one of the basic statistics used to ascertain biological diversity. Traditionally ecologists have used the number of species observed in a sample, S0 , to estimate S , realizing that S0 is a lower bound for S . One alternative to S0 is to use a nonparametric procedure such as jackknife resampling. For species richness, a closed form of the jackknife estimator is available. Typically statistical software contains only the traditional iterative form of the jackknife estimator. The purpose of this article is to propose an S-PLUS function for calculating the noniterative first order jackknife estimator of species richness and some associated plots and statistics.