364 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



August 1953, Holt (PCII 495); Sinking Creek in Horse Cove, January 10, 1954, 

 Holt (PCH 580). 



North Carolina: watatjga county: 2 miles south of Vilas on N.C. Hy. 194, 

 June 14, 1950, Hobbs and Hart (PCH 350). 



Virginia: augusta county: South River, 2.4 miles south of Waynesboro, 

 September 3, 1948, Hobbs (PCH 271). craig county: 1.4 miles west of New- 

 castle on Va. Hy. 311, June 23, 1948, Hobbs (PCH 99). franklin county: 

 Smart View Picnic Area, Blue Ridge Parkway, September 14, 1958, Holt and 

 Hoffman (PCH 891). giles county: Cascades of Little Stony Creek, June 25, 

 1952, Holt (PCH 492, paratypes). grayson county: Tributary to Big Wilson 

 Creek, 4 miles south of Mouth of Wilson, June 14, 1950, Hobbs and Hart (PCH 

 339, types), lee county: Hardy Creek, 11.1 miles west of Jonesville on U.S. 

 Hy. 58, June 16, 1950, Hobbs and Hart (PCH 371). rockingham county: 

 Swift Run, 3 miles east of Elkton, December 1946, Holt (PCH 4). smyth 

 county: V/hite Top Mountain, September 5, 1951, John T. Wood (PCH 531). 

 TAZEWELL COUNTY: Blucstoiie River, 11.2 miles northeast of Tazewell on U.S. 

 Hy. 460, June 18, 1950, Hobbs and Hart (PCH 393, paratypes); Burkes Garden, 

 June 30, 1947, R. L. Hoffman and H. I. Kleinpeter (PCH 532) ; Maiden Spring 

 Creek, 1 mile east of Wardell, June 19, 1959, Hoffman (PCH 904). Washington 

 county: 9.5 miles south of Abingdon on U.S. Hy. 11, April 14, 1951, Hobbs and 

 West (PCH 432); 4.8 miles south of Abingdon, April 14, 1951, Hobbs and West 

 (PCH 435); North Bristol, January 1, 1954, W. A. Whittaker (PCH 581). wythe 

 county: Reed Creek, 3.3 miles southwest of Wytheville on U.S. Hy. 11, April 14, 

 1951, Hobbs and West (PCH 439). 



West Virginia: Greenbrier county: Dry Creek, east side of Kates Mountain 

 at White Sulphur Springs, July 3, 1947, Hobbs (PCH 294). pendleton county: 

 5.8 miles east of Franklin on U.S. Hy. 33, July 30, 1949, Hobbs and Word (PCH 

 275). WYOMING county: Barker Creek, 5.3 miles south of Tralee, July 12, 1947, 

 Hobbs and Wilson (PCH 95). 



From the standpoint of major drainage systems, the vast majority 

 of the preceding records lie within the basins of the upper Tennessee 

 and Kanawha rivers, and southwest Virginia clearly seems to be the 

 center of abundance for this species. Peripherally, the records are 

 distinctly more spotty, although in equally well-collected areas. 

 Towards the northeast, the species occurs in the James and Potomac 

 drainage systems. 



The single known locality for Kentucky lies in a region which was 

 intensively collected by Dr. Holt during July 1958, a fact which 

 permits the inference that heterognatha may exist in central Kentucky 

 only as a relict, and this fact, together with the generally sporadic 

 distribution of species suggests that the range may be in the process 

 of contraction, perhaps as a result of post-Pleistocene increase in 

 temperature in the southern Appalachians. 



Nonetheless, it must be emphasized that the distribution of het- 

 erognatha is by no means well-known, and many new localities doubt- 

 less remain to be established. 



Kemarks.^ — -It has ah-eady been observed that heterognatha is 

 endowed with a remarkable combination of presumably evolutionary 

 specializations. It is one of the easiest of branchiobdellids to recog- 



