138 U.S. NATIONAL MUSEUM BULLETIN 282 



six gill rakers. The head length is stepped into the standard length 

 3.25 times and 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 1.8 times. Table 28 gives further measurements. 



Etymology. — This subspecies was named hildebrandi in honor of 

 the late Dr. Samuel F. Hildebrand, an outstanding American ichthy- 

 ologist. 



Distribution. — Noturus h. hildebrandi ranges from the Homochitto 

 River system northward in Mississippi. It intergrades with Noturus 

 hildebrandi lautus in northern Mississippi and southwestern Tennessee. 

 The populations in the Homochitto and Bayou Pierre are relatively 

 uniform and are regarded as typical. Intergrades from the Yazoo 

 drainage in northern Mississippi vary toward Noturus hildebrandi 

 lautus, but those from the southern portion of the system closely 

 approach typical hildebrandi morphologically. 



Ecology. — In southern Mississippi Noturus hildebrandi hildebrandi 

 is typically found in relatively shallow, clear, gravelly or small pebble- 

 bottomed riffles with moderate to swift current. It has been collected 

 frequently with Noturus miurus. 



Noturus hildebrandi lautus, new subspecies 



Plates 4 (fig. 2), 10 (fig. 2); Map 9 



Types.— USNM 201665 (holotype), USNM 193470 (16) andUMMZ 

 187093 (4) (totaling 20 paratopotypes, 36-47 mm. standard length), 

 collected from North Fork of Obion River, at Tennessee Highway 69, 

 Henry County, Tennessee, July 27, 1954, by C. E. Ruhr and party. 



Other paratypes 



UNITED STATES: Tennessee: Forked Deer River system ; Obion drainage: 

 USNM 197395 (4, 24-44), North Fork Obion R., Campground Levee Crossing, 

 Weakley Co., September 15, 1954, C. E. Farrell. USNM 197402 (2) and UMMZ 

 187092 (2) (totaling 4, 35-48), Middle Fork Obion R., Hwy. 6, Gleason Crossing, 

 Weakley Co., September 16, 1954, C. E. Farrell. KU 9751 (2), Middle Fork 

 Obion R., 4.5 mi. W., 1 mi. S. Paris, Henry Co., April 5, 1965, F. B. Cross. KU 

 10036 (3), Middle Fork Obion R., Hwy. 22, Weakley Co., September 7, 1964, 

 Cross. 



Other material studied 



UNITED STATES: Tennessee: Hatchie River system: USNM 190746 

 (18, 18-44), Moss Cr., on Rose Creek Road, 1.3 mi. N. Hwy. 57 or about 2.5 mi. 

 ENE. Pocahontas, McNairy Co. USNM 190775 (6, 15-42), Spring Cr., 1.2 mi. 

 S. Bolivar, Hwy. 125, Hardeman Co. USNM 193464 (1, 40), Moss Cr., about 

 4 mi. W. Selmer, McNairy Co. Vanderbilt U (1, 32), Big Black Cr., Madison Co. 

 South Forked Deer River system: USNM 193479 (2, 42-44), Deer Cr., Huron, 

 Henderson Co. 



Diagnosis. — Noturus hildebrandi lautus differs from Noturus hilde- 

 brandi hildebrandi in having a relatively short head stepped 3.4 to 

 4.1, usually 3.6 to 3.9 times in standard length; modally ten preoper- 



