Fig. 3. Comparison of model results of species richness with the observed species richness derived from collection points. The numbers above the points represent the number of cells with those characteristics (total n = 908). The section marked "Model Under-Estimate" is the area where all points are falsely predicted positive occurrences. Points along the line and in the portion marked "Potential Under-Collection" could be any of correctly predicted positive occurrences, falsely predicted negative occurrences, or correctly predicted negative occurrences. It is assumed that, given the validity of the model, these areas represent already visited grid cells that potentially harbor more species than so far encountered.