864 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
feet south of mouth of Burnett Creek, Shooks Gap (T.V.A. 147-NE) Quad- 
rangle. 
Arline formation in Virginia: 4 mile south of McMullen switch, 4 miles south- 
west of Marion, Marion (T.V.A. 218-SE) Quadrangle. 
Athens formation (base) in Tennessee: Just east of the road intersection 25 
miles south-southeast of Riceville, Calhoun (T.V.A. 125-SW) Quadrangle; 
600 feet S. 4o° E. of the railroad-highway intersection 1 mile northeast of the 
courthouse in Athens, Athens (T.V.A. 125-SE) Quadrangle; Tennessee High- 
way 60, 54 miles east of Cleveland, East Cleveland (T.V.A. 131-SW) Quad- 
rangle ; Craighead Creek, 4 mile north of Christiansburg, Sweetwater (T.V.A. 
131-SW) Quadrangle; road along Meadow Fork, east of junction, 25 miles 
northeast of Calhoun, Calhoun (T.V.A. 125-SW) Quadrangle. 
Fetzer tongue in Tennessee: Bend of the road 1.3 miles south of Sevierville, 
Pigeon Forge (T.V.A. 156-SE) Quadrangle. 
Botetourt limestone in Tennessee: 25 miles southeast of Whitesburg, Bulls 
Gap (T.V.A. 171-SE) Quadrangle. 
Same in Virginia: Junction of Virginia Highways 311 and 114, 4 mile south- 
west of Catawba, Salem (15’) Quadrangle; 4 miles southwest of Bland, Bland 
County. 
Effna-Rich Valley formations in Virginia: At Porterfield Quarry, 5 miles 
east of Saltville, Maccrady (T.V.A. 218-NW) Quadrangle. 
Edinburg formation (Crytonotella zone) in Virginia: In the ravine at the 
switch about § mile east of Strasburg, Strasburg (15’) Quadrangle; near the 
dam on Shenandoah River, 14 miles N. 61° E. of Edinburg, Edinburg (15’) 
Quadrangle. 
Same formation (Nidulites zone) in Virginia: 100 yards south of Battlefield 
Crystal Caverns entrance on U. S. Highway 11, Hupp Hill, 1 mile north of 
Strasburg, Strasburg (15’) Quadrangle. 
Youngman formation in Vermont: In Mississquoi Park, Highgate Springs, 
St. Albans (15’) Quadrangle. 
Discussion.—This species is characterized by its longitudinally subrectangular 
outline, strongly umbonate pedicle valve, deeply concave brachial valve, and gen- 
erally somewhat broadly rounded front. This species is so unlike C. platys in its 
profiles and outline that further comparison is unnecessary. Its brachial valve 
appears to be much more concave than that of C. trentonensis. The species is 
most like C. auriculata, but it does not have as strong a development of the cardi- 
nal extremities as that species, nor does it usually attain the large size of the 
Oranda species. The lateral margins of C. subquadrata are never concave in- 
ward and usually vary from nearly parallel to gently divergent anteriorly. The 
species is thus usually wider at the front than is customary in the Oranda species. 
Christiama subquadrata is a very variable species as can be seen from the 
large collections from Friendsville. At this place it may often be picked up in 
the dirt by the hundreds, the specimens having been washed by rain from the 
residual soil resulting from decomposition of the Arline limestone. The Friends- 
ville forms vary from nearly parallel sided to specimens having anteriorly diver- 
