PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 893 
MACROCOELIA DUPLISTRIATA (Willard) 
Plate 173, F, figure 31; plate 236, B, figures 8-12; plate 249, B, figures 10-12 
Rafinesquina duplistriata Wrttarp, Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, No. 6, 
p. 281, 1928. 
Willard designated two specimens as cotypes. One of these is a pedicle valve 
showing the exterior and preserving the profile. The other is an interior of a 
brachial valve showing the subperipheral thickening and the 5 ridges associated 
with the adductor field. Inasmuch as the specific characters chiefly appear on the 
exterior of these shells, pedicle valve M.C.Z. 8621 is chosen as lectotype for the 
species. 
Evidence in the National Collection indicates that this species attained a large 
size. One large brachial interior has a width of 70 mm. The species seems to 
be variable in lateral profile. 
Figured hypotypes.—117767, 117768, 117769, 117770, 117771. 
Horizon and locality—Lincolnshire formation in Virginia: Near Goodwins 
Ferry on New River, Giles County ; Speers Ferry, Clinchport (T.V.A. 188-NW) 
Quadrangle. 
Same horizon in Tennessee: 4 mile north of Eidson, Kyles Ford (T.V.A. 
170-SE) Quadrangle. 
Lincolnshire formation (Hogskin member) in Tennessee: 0.4 mile northeast 
of Red Hill, 44 miles west-southwest of Thorn Hill, Avondale (T.V.A. 162-SW) 
Quadrangle; on U. S. Highway 25E, north of Thorn Hill, Avondale (T.V.A. 
162-SW) Quadrangle; just above Sowerbyites zone, 4 mile east of Beech Grove 
Church, 3 miles west-southwest of Thorn Hill, Avondale (T.V.A. 162-SW) 
Quadrangle; Sally Cleveland Farm, $ mile southwest of Washburn, Dutch Val- 
ley (T.V.A. 154-SE) Quadrangle; 90 to 120 feet above the “Mosheim”’ lime- 
stone on U. S. Highway 25E, north of Hayes’ house, 1 mile north of Indian 
Creek, Evans Ferry section, Howard Quarter (T.V.A. 162-NW) Quadrangle ; 
upper Lincolnshire formation, # mile southwest of Mount Eager Church, 
Hogskin Valley, Powder Springs (T.V.A. 154-SW) Quadrangle. 
MACROCOELIA ELEGANTULA Cooper, new species 
Plate 233, C, figures 7-12; plate 235, C, figures 5-16; plate 247, D, figures 11-13 
Medium sized for the genus, attaining a width of about 14 inches; wider than 
long with the hinge varying from shorter to wider than the midwidth; sides more 
or less oblique; anterior margin strongly rounded; surface costellate, costellae 
alternating in size, about 3 to the millimeter at the front margin. 
Pedicle valve strongly convex in lateral profile and with the maximum con- 
vexity at the middle; anterior profile strongly domed; beak small; umbo nar- 
rowly swollen to form a short, low fold; posterior third gently swollen, median 
third strongly swollen to form the most convex part; anterior slope gently con- 
vex, long and steep; lateral slopes steeper than the anterior one. Interarea short 
and curved; pseudodeltidium small and short. Muscle field heart shaped, oc- 
cupying the posterior third; median ridges strong. 
