108 J. E. Cooper and A. L. Braswell 



cambarus) rusticus (Girard)] by Hobbs and Walton (1966) and 

 Hobbs et al. (1967), occurs in the New-Kanawha basin of Virginia 

 (Hobbs, in litt.). This animal also has been taken in New River 

 headwaters at the following North Carolina localities: Alleghany Co. — 

 (1) small stream entering New R just E US 21-221, ca. 0.2 air mi 

 (0.3 air km) S Virginia state line, 3.0 air mi (4.8 air km) NNE jet US 

 21 & 221 at Twin Oaks; 1 ovig 9 (NCSM C-284), 20 May 1978, 

 REA, Jr, JEC. Ashe Co.— {2) South Fk New R at SR 1602, ca. 0.6 air 

 mi (1.0 air km) SE jet US 221, 2.6 air mi (4.2 air km) ENE town 

 Nathans Creek & 7.8 air mi (12.4 air km) NE cntr Jefferson; 3 8 II, 2 

 j 8, 4 9 (NCSM C-257), 20 Jul 1978, DSL; (3) South Fk New R at 

 E side NC 88 bridge and along SR 1588, ca. 0.5 rd mi (0.8 rd km) 

 NE Orion & 4.8 air mi (7.6 air km) E West Jefferson; 2 8 I, 1 8 II 

 (NCSM C-276), 1 ovig 9 (NCSM C-277), 1 8 II (NCSM C-256), 

 21 May 1978, REA, Jr, JEC; (4) South Fk New R along CR 1566, 

 0.3 rd mi (0.5 rd km) S jet SR 1567; 2 ovig 9 (NCSM C-803, 804), 

 4 8 II (NCSM C-805), 20 May 1978, REA, Jr, JEC; (5) South Fk 

 New R at NC 221, ca. 1.7 air mi (2.7 air km) WSW Scottsville; 1 j 8, 

 2 9 (NCSM C-2358), 27 May 1985, F. Winborne, DRL; (6) 

 Buffalo Crk near confluence Little Buffalo Crk, ca. 2.5 mi (4.0 km) 

 W cntr West Jefferson; 1 j 8 (NCSM C-2355), 30 May 1985, 

 DRL, FW; (7) Dog Crk at SR 1592, 4.0 mi (6.4 km) E Jefferson; 1 j 

 9 (NCSM C-508), 6 Aug 1978, J. R. Clamp, M. Dennis. 



This species was very common at locality (3), where it occurred 

 in close association with another large crayfish, Cambarus {Hiati- 

 cambarus) chasmodactylus James. The two often were found under 

 the same cover, usually medium-size to large rocks in cold, fast- 

 moving water, and in the same gravel riffles. Both species also 

 occurred together at locality (2). At locality (4), the Orconectes was 

 collected with C. chasmodactylus and C. robustus. 



Procambarus (Ortmannicus) medialis Hobbs 

 Procambarus {Ortmannicus) pearsei (Creaser) 

 Procambarus {Ortmannicus) plumimanus Hobbs and Walton 

 These three species comprise a "disjunct" enclave at the northern 

 periphery of the range of the Planirostris Group of the genus 

 Procambarus, a fact that is of considerable importance in under- 

 standing the evolutionary history of the group. Hobbs (1975:15) 

 summarized their distributions: "The Neuse River basin appears to 

 mark the southern limit of the range of P. medialis, the northern 

 [Northeast] Cape Fear River basin marks the southwestern limit of 

 the range of P. plumimanus, and the range of P. pearsei encom- 



