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in the mainstream Colorado River near Yuma ("Fort Yuma," Jordan and Everman, 1986; see also Meek, 1904 and Follett, 1961); thence upstream to the Virgin River system in Utah (Fig. 1). However, from biological considerations alone, there is good reason to believe that woundfin occurred further upstream on the Verde, Salt, and Gila rivers. As detailed by Miller and Hubbs (1960), the stated type locality "San Luis Valley, Western Colorado (Cope 1874)," was an obvious error, many ~!, of which were perpetrated by collectors associated with the Wheeler Survey in 1871 to-1874. Miller and Hubbs also rejected as erroneous locality data the records from the "Colorado Chiquito River, Arizona" (Bohlke, 1953) on the basis of no other indications that the fish ever inhabited that stream. The Wheeler expedition maintained a base at Toquerville, Washington County, Utah, in 1872, on LaVerkin Creek (Wheeler, 1889), from where they worked in the Virgin River canyon and traveled to St. G+~orge. It seems likely that the type series of P. argentissimus was taken from the mainstream Virgin River (Miller and Hubb, 1960). PRESENT DISTRIBUTION Woundfin range from LaVerkin Springs on the mainstream of the Virgin River and the lower portion of LaVerkin Creek in Utah, downstream to Lake Mead, Nevada (Fig. 2). A single specimen was taken from the middle Moapa River, Clark County, Nevada, in the late 1960's (Deacon and Bradley, 1972). The Moapa River was formerly a tributary to the Virgin River, but both streams now flow into Lake Mead. The species has been transplanted into four localities in attempts to establish populations. In one locality, the Hassayampa River in Arizona, reproduction occurred in the summer of 1972 but a flood in September of 1972 evidently destroyed the entire pop- ulation because subsequent collecting efforts have failed to yield any woundfin (Minekley, pers. comm., 1977). In March, 1972 they were also placed in the Salt River, Arizona, but none have been taken there since. ~: In Sycamore Creek, Agua Fria drainage, Arizona, a few specimens stocked. in spring, 1972 survived-the severe flooding of 1972-3, and two individuals collected in late August, 1973 were gravid. None has been collected in Sycamore Creek since 1973. The fourth locality,-the Paria River, Arizona- Utah, was stocked several times between 1969 and 1972. No woundfin were found during surveys in May, 1974 and May, 1975 (Unpub. Data, Arizona Game ~', and Fish Stocking Records). HABITAT REQUIREMENTS ~~ Woundfin are most often collected from runs over sand bottoms, usually near some type of cover, where the average water depth is 25 cm (+19) and where the average current is 0.42 m/sec (+0.28) (Cross, 1975). They appear to prefer physically unmodified habitats, but are found in areas that have been greatly modified. Woundfin reach peak abundance in areas of mobile sand bottom where the substrate shifts slowly downstream under the influence of near-laminar currents. Depths preferred by the species 3 appear to range from 5 to 35 centimeters but disturbed fish move rapidly