Peromyscus eremicus (Baird, 1858) . Mammalia in Repts. U.S. Expl. Surv., 8(1):479.

TYPE LOCALITY: USA, California, Imperial Co., Old Fort Yuma, Colorado River opposite Yuma, Arizona .

DISTRIBUTION: S California east to Transpecos Texas, USA, most of Baja California peninsula, south along coast to C Sinaloa and on the Mexican Plateau to N San Luis Potosi, Mexico.

SYNONYMS: alcorni, anthonyi, arenarius, avius, cedrosensis, cinereus, collatus, fraterculus, herronii, homochroia, insulicola, nigellus, papagensis, phaeurus, polypolius, propinquus, pullus, sinaloensis, tiburonensis.

COMMENTS: Relationships of P. eremicus to various insular forms in Gulf of California elucidated by Lawlor (1971a, b; 1983), who relegated collatus to a subspecies. Genetic variation surveyed by Avise et al. (1974b), who noted differentiation of eremicus populations east and west of the Colorado River. Once included P. merriami (see Hoffmeister and Lee, 1963) and P. eva (see Lawlor, 1971a). See Veal and Caire (1979, Mammalian Species, 118). P. eremicus species group.