A description of this species, which is endemic to Neosho River, has been prepared but not yet published by Dr. W. Ralph Taylor. I found the Neosho madtom only at the middle station in 1958 and 1959, and at the lower station in 1959, where the species was common in shallow water having moderate current over clean gravel bottom. Specimens were most effectively collected by digging into the gravel above the seine and allowing the gravel to wash into the seine. In 1952, Cross (1954:311) found this species in abundance in riffles at the confluence of the South Fork and Cottonwood River, and at several other localities in the Neosho mainstream (personal communication). The Neosho madtom is nearly restricted to gravel riffles having moderate flow; therefore, it may be drastically reduced by intermittency of flow. I found none in 1957 and few in 1958. By 1959, the third summer of continuous flow, the Neosho madtom was again common. #Fundulus notatus# (Rafinesque) Black-striped Topminnow The black-striped topminnow was rare in the mainstream at the lower Marais des Cygnes and the middle and lower Neosho stations, where it was found in quiet water near shore. Near the middle Neosho station, a large population was present in an oxbow lake that is frequently flooded by the river. #Labidesthes sicculus# (Cope) Brook Silversides The brook silversides occurred rarely at the lower Marais des Cygnes and at the middle and lower Neosho stations. #Micropterus dolomieui# Lacépède Small-mouthed Bass One individual was taken at the lower Neosho station in 1957. #Micropterus punctulatus punctulatus# (Rafinesque) Spotted Bass The spotted bass occurs in Kansas only in the southeastern part of the state--in southern tributaries of the Osage system, in Spring River drainage, and in relatively clear streams of the Flint Hills. At my stations on the Neosho River, this fish was more abundant in 1957 than in 1958 or 1959. Spotted bass were taken most frequently over rubble bottom or near boulders in moderate current. Collections made in the evening or early morning more often contained spotted bass than collections made at other times of day (Table 9). Data from a few specimens that were marked, released, and recaptured indicated that the species is relatively sedentary; therefore, the greater abundance in the morning and evening collections probably indicates increased activity during these periods, possibly in connection with feeding. The spawning season in 1957 may have continued as late as 10 July when a ripe female 11.3 inches T. L. was taken. Young-of-the-year were taken on 24 June in moderate current over gravel bottom and in quiet water over mud bottom.