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Changing Fish Fauna of the Southwest 387 w 1 dinary fish is confined to a single cave-spring hole in Ash Meadows, Nevada. In its small population size it is nearly unique among verte- brates (matched only by the whooping crane) and is peculiar in lack- ing pelvic fins, in the small size attained (mature at 15-20 mm., stand- ard length), and in its coloration and life colors. The temperature of its restricted habitat fluctuates narrowly between 91° and 93° F., and the tiny fish occur only rarely to a depth of 50 feet, although the pool is more than 150 feet deep. The total population of this species proba- bly varies between 100 and 300 individuals; a rather accurate esti- mate of a total population of 160 fish, of which approximately 100 were adults representing the effective breeding population, was made recently (Miller, in press). This species has been able to maintain itself over many thou- sands of years because of the isolation of its habitat in a rather re- mote desert area. However, in order to prevent a man-made catastro- phe from eliminating the species, the Devil's Hole area (40 acres) was . added to Death Valley National Monument early in 1952. Even so, a species with a home range much smaller than that of a back- yard swimming pool must be considered .endangered. Cyprinodon elegans Baird and Girard, Comanche Springs pup- fish.-This distinctive species was based on a series of both sexes taken in 1851 from Comanche Springs at Fort Stockton, Texas. Al- though the type locality of C. bovinus (Leon Springs) is less than 10 miles distant, the 2 species are remarkably different. C. elegans was common in Comanche Springs on September 15, 1938, when Carl L.. Hubbs and party collected 110 specimens. Although the springs stopped flowing during the summer of 1951, after a prolonged period of drought, Cyprinodon still persisted in pools in the outlet ditch in April 1952 (observation by Earl S. Herald), and specimens were col- lected at Comanche Springs by Frank T. Knapp and class on July 30, 1952 (material at Texas A & M College). However, by October, 1956, Clark Hubbs found the springs and outlet to be completely dry, with no trace of fish life. The largest of the spring pools was about 100 by 400 feet in major dimensions and the total spring flow, in 1938, was stated to be 35 million gallons daily, which is approximately 54 second-feet, since a second foot of water is equal to about 646,000 gal- Ions per day (Meinzer, 1927, p. 3). The discharge, in second feet, was 66 in the summer of 1899, 64 on July 26, 1904, and 44 on August 21, 1919 (Meinzer, 1927, p. 41). 4.