UPPER TENNESSEE DRAINAGE. 529 



also goes into the lower Powell, up to Claiborne Co., Tenn. From 

 the Holston, it goes in the lower parts of the North and South Fork: 

 but at and near its upper limit, it always intergrades with the next 

 form ( bursa-pastoris) . 



Type locality: Caney Fork River, Tenn. (and Holston River, 

 Tenn.). (Thus it seems to exist also in the Cumberland drainage, 

 but this requires further investigation. Wilson and Clark, '14, do 

 not mention it.) 



4. FUSCONAIA PILARIS BURSA-PASTORIS (Wright), 1896. 



Unio bursa-pastoris Wright, '96. — Uiiio kirtlandianus Pilsbry & 

 Rhoads, '96. — Fusconaia bursa-pastoris Ortmann, '13a, p. 90 

 (anatomy), and '13&, p. 311. — Fusconaia bursa-pastoris Good- 

 rich, '13, p. 93. — Ouadrula bursa-pastoris Simpson, '14, p. 890. 



This is the compressed headwaters-form of F. pilaris, connected 

 with it through the intermediate form lesueuriana. It has the same 

 relation to F. pilaris, as has F. kirtlandiana (Lea) of the upper Ohio 

 drainage to F. subrotunda ; it is practically the same thing, except 

 that it does not reach the size of it, and does not develop the " wing" 

 seen on the posterior upper margin of kirtlandiana. It is perfectly 

 clear that the form mentioned by Pilsbry & Rhoads from Watauga 

 River, Johnson City, Tenn., is this, and, indeed, I have found it 

 very close to this locality. 



The diameter of this form is less than 45 per cent, of the length, 

 and it appears as if the lack in this direction is compensated by a 

 greater circumference of the shell, bursa-pastoris often reaching a 

 size (length and height) not seen in either pilaris or lesueuriana. 



The metropolis of this form is in Clinch River ; a few specimens 

 have been found in the lower Clinch, in Knox and Anderson Cos. 

 (associated with lesueuriana and even pilaris) ; farther up, from 

 Claiborne Co., Tenn., into Virginia, it becomes more and more 

 abundant, and north of the state line, where lesueuriana disappears 

 (only found at Clinchport), it is developed as a pure race, going up 

 into the headwaters as far as Cedar Blufif, Tazewell Co., Va. In 

 Powell River, similar conditions prevail; in the lower Powell it is 

 found associated and intergrading with lesueuriana, but north of the 



