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12 on these subspecies to determine the need of listing for their protection. Relictus solitarius: Relict (Steptoe) Dace This animal is the only native fish species in the entire region composed of Butte, Goshute, Ruby and Steptoe Valleys. The species as a whole has experi- enced reduction in localities through most of its range over the past several years as a result of both exotic fish introductions and habitat alterations. The distribution of dace in Butte Valley was checked in the fall of 1979, with the apparent loss of two populations at Stratton Ranch and Wrights Springs. The springs at the former locality were modified into three large stock ponds, and the outflows were heavily utilized by cattle. Wrights Springs have lost most of their discharge, with many of the old channels now being dry. The remaining outflows were heavily polluted by cattle, and collections for many miles produced no speciments. The other locations within Butte Valley con- tained fair numbers of dace, although the habitats continue to be modified. The Goshute Valley population at Twin Springs is in good condition, although heavily impacted by cattle. The springs on the Johnson Ranch in the northern extremities of the valley were not surveyed, as the owner would not permit sampling. The Ruby Valley populations have been the most seriously impacted, with dramatic losses in both numbers and localities. Once the only species in all the expanse of the marsh and associated springs, they have been extirpated from all but a few isolated spring systems. Efforts should be made to pro- tect these sites, as the Ruby Valley form of the dace is very different from those in the other valleys. The Steptoe Valley populations have also been highly impacted by exotic species and habitat alterations. The Dairy Springs location is represented by a single specimen collected in the fall of 1979• Specimens were not found at four known locations in recent field collections. Local personnel of the Nevada Department of Wildlife examined the Grass Springs locality in 1977-78 and found only 5 springs out of 25 that still contained dace. I found none in the fall of 1979. The Spring Valley populations are considered to be introduced, and those localities collected all had healthy populations. In summary, this species is experiencing widespread loss of both popula- tions and habitat and stands to be heavily impacted by the proposed MX missile system. Life history studies should be undertaken as soon as possible to establish background information for this animal. In view of the current status of this animal and its habitat, it should be listed as threatened or of special concern. Rhinichthys osculus lethoporus: Independence Valley Speckled Dace The subspecies is confined to the single fish-inhabited system in Warm Springs in this Valley. This system, as indicated for Gila bicolor isolata, has been heavily impacted by exotic fish and habitat modifications. The current status of this species is unknown at this time, and habitat surveys as well as life history studies should be initiated.