Open Source Software (OSS) projects are typically the result of collective efforts performed by developers with different backgrounds. Although the quality of developers' contributions should be the only factor influencing the evaluation of the contributions to OSS projects, recent studies have shown that diversity issues are correlated with the acceptance or rejection of developers' contributions. This paper assists this emerging state-of-the-art body on diversity research with the first empirical study that analyzes how developers' perceptible race and ethnicity relates to the evaluation of the contributions in OSS. We performed a large-scale quantitative study of OSS projects in GitHub. We extracted the developers' perceptible race and ethnicity from their names in GitHub using the Name-Prism tool and applied regression modeling of contributions (i.e, pull requests) data from GHTorrent and GitHub. We observed that among the developers whose perceptible race and ethnicity was captured by the tool, only 16.56% were perceptible as Non-White developers; contributions from perceptible White developers have about 6-10% higher odds of being accepted when compared to contributions from perceptible Non-White developers; and submitters with perceptible non-white races and ethnicities are more likely to get their pull requests accepted when the integrator is estimated to be from their same race and ethnicity rather than when the integrator is estimated to be White. Our initial analysis shows a low number of Non-White developers participating in OSS. Furthermore, the results from our regression analysis lead us to believe that there may exist differences between the evaluation of the contributions from different perceptible races and ethnicities. Thus, our findings reinforce the need for further studies on racial and ethnic diversity in software engineering to foster healthier OSS communities.