Analysis of a Population of the Tropical Freshwater Shrimp, Atya scabra (Leach)

During the course of recent investigations on the biology of Mexican streams, the writer secured two samples from a population of the little known tropical freshwater shrimp, Atya scabra (Leach). A review of the literature has revealed little information published in this country on the ecology of this crustacean. Ortmann (1894) discussed the distribution of the species, and Allee and Torvik (1927) mentioned its presence in pools of a creek in the Panama Canal Zone. Of the foreign papers, that by Villalobos (1943) is of interest. In this excellent morphological study the collecting method and the habitat of the shrimp in the Rio Necaxa near Coyutla in the state of Vera Cruz, Mexico were discussed. In view of the limited knowledge of the ecology of Atya scabra and the uncertain possibility of obtaining additional specimens in the near future, the writer feels justified in publishing this brief population analysis based upon the small samples available. Acknowledgments.-The author takes this opportunity to thank Dr. Fenner A. Chace, Jr., of the U. S. Natioonal Museum for making specific determinations of the shrimp and for criticizing the manuscript. The author is grateful also to Mr. Everts W. Storms, who was his host in Mexico. Original field work for the present study was conducted under a grant from the Tozer Foundation of the University of Minnesota, and further field bbservations were carried out under a grant from the Tulane University Council on Research. The author wishes to express his appreciation to these supporting institutions.