6 John E. Cooper and Ray E. Ashton, Jr. 



older larvae, drawn by Renaldo G. Kuhler, scientific illustrator at the 

 state museum. 



Ashton et al. (1980) reported electrophoretic analyses of 17 loci 

 coding for enzymes in 20 N. lewisi, 8 unspotted N. punctatus from the 

 Neuse River drainage, 8 spotted N. punctatus from the Lumber-Pee Dee 

 drainage, and 21 N. maculosus (1 from North Carolina). They con- 

 cluded (p. 46): "the specific status of N. lewisi is confirmed by electro- 

 phoretic data as well as by the distinct larvae described by Ashton and 

 Braswell (1979). Further, N. punctatus appears to have been reproduc- 

 tively isolated from sympatric N. lewisi and from allopatric N. maculo- 

 sus for a considerable period of time, and spotted N. punctatus from the 

 Pee Dee drainage (North and South Carolina) appear on the basis of 

 electrophoresis to be genetically similar to the unspotted populations of 

 the Neuse River system." 



Color photographs of adult N. lewisi were provided by Behler and 

 King (1979) and Martof et al. (1980). 



THE HYDROLOGIC UNITS 



Both the Neuse and Tar river systems head in the eastern Piedmont 

 Plateau of the state, drain generally southeast through the Coastal 

 Plain, then debouch at broad, fairly deep, saline estuaries that feed into 

 Pamlico Sound. Approximately one-third of each river basin lies in the 

 Piedmont Plateau and Fall Line Zone (which is some 30 to 40 miles 

 wide), and two-thirds of each basin is within the Coastal Plain. Not 

 unexpectedly, the characteristics of the upper hydrologic units differ 

 considerably from those of the lower basins. The Piedmont Plateau 

 tributaries flow through valleys of various depths between rolling hills. In 

 the main, their banks are somewhat precipitous, their floodplains com- 

 paratively narrow, and their waters graphically lotic, with a combina- 

 tion of pools and rocky or gravelly rapids and riffles. Substrates are 

 sand-gravel or sand-silt. Bayless and Smith (1962) recorded average 

 Piedmont stream gradients of from 14 to 19 feet per mile for the Eno, 

 Flat, and Little rivers, all of them Neuse feeders, and 2 feet per mile for 

 the mainstem Neuse. The average Piedmont gradient for the Tar was 

 reported as 2.8 feet per mile (Smith and Bayless 1964). 



By contrast, the Coastal Plain tributaries of both rivers flow 

 through flatter terrain and have broader floodplains. Their slow-moving 

 waters have a low average gradient (0.6 feet per mile for the Neuse; 

 Bayless and Smith 1962). The larger Coastal Plain tributaries often have 

 high banks and bluffs on their south side, and broad flats and swamps 

 on their north side (Stuckey 1965). The substrates of these streams are 

 muck, sand, and detritus. The Coastal Plain streams and rivers are 

 underlain with relatively soft sedimentary bedrock of from Cretaceous 

 to Recent age. In the Fall Line Zone this gives way to a bedrock con- 



