208 U.S. NATIONAL MUSEUM BULLETIN 2 82 



eleven recurved serrae on the left and twelve on the right on the 

 posterior edge of the pectoral spine, and many well-developed but 

 smaller serrae on the anterior edge. The body form and pattern 

 of pigmentation of this specimen is shown in plate 20, figure 2. The 

 head length is stepped into the standard length 3.4 times. The 

 distance from the adipose notch to the tip of the caudal fin is stepped 

 into the distance from the dorsal origin to the adipose notch 1.65 

 times. Other measurements are given in table 28. 



Variation. — N. Jlavater in the Current River closely approaches 

 geographically localities from which N. miurus has been collected 

 in the Little Black and Black Rivers, Missouri. In these areas there 

 is a sharp break in characters between the two species and no inter- 

 breeding of the populations is indicated. 



Populations of Jlavater from the White and Current Rivers, although 

 presumably rather widely separated appear to be identical. 



Total caudal rays in 36 specimens from the upper White River 

 are 51 to 59, and in five from the Current River 54 to 60; rays in 

 the upper half of the caudal fin are 26 to 31 in the White and 29 to 

 32 in the Current; soft pectoral rays are 7 to 9, usually 8 in the White 

 River system, but there are 7 rays in 3 fins and 8 rays in 6 from the 

 Current River system. Other data from the upper White River speci- 

 mens overlap those from the Current. No significant variational 

 trend is known to exist. 



Distribution. — Noturus jlavater (map 14) is confined to the 

 upper White River system in Arkansas and Missouri. It is found 

 in the upper Current River; the adjacent Black River contains 

 Noturus miurus. From the Current it ranges southwesterly through 

 most of the Ozark streams to the headwaters of the White River. 



The record (Meek, 1894a) from Sallisaw River near Makey's 

 [McKey's] Store, Oklahoma, is undoubtedly based upon transposed 

 data. Dr. George A. Moore has loaned a specimen of Noturus miurus 

 that he took from this locality. 



Etymology. — The name Jlavater (Latin) is from Jlavus (yellow) 

 and ater (black), and refers to the black and yellow colors. 



Relationship. — Noturus Jlavater is obviously an aUopatric rep- 

 resentative of N. miurus and N. Jlavipinnis. The general similarity 

 of color pattern, the morphology, and especially the numerous caudal 

 rays align Jlavater with the miurus group. 



Ecology.— A^^. Jlavater lives in clear, possibly cool, water of mod- 

 erate to rapid current, flowing over a gravel, rubble, and boulder 

 bottom. It seems to prefer the deeper portions of streams or pools 

 rather than the shallow riffles. Specimens have been taken in collec- 

 tions with exilis and albater. 



