Southwestern U.S.A. (Arizona, New México), México (Baja California, Baja California Sur): Two weeks (16–31 May, 2004), funded by the Richard Lounsbery Foundation. AMNH Scientific Assistant Randy Mercurio, joined Dr. Michele Nishiguchi (University of New México, Las Cruces), colleagues, and students for a trip of ca. 5,300 km through the desert and semidesert habitats of Arizona, New México, Baja California and Baja California Sur. Mercurio collected ca. 250 myriapods, scorpions and spiders, including some important endemic genera and species, for the REVSYS project.