812 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Exterior of pedicle valve unknown. 
Interior: A fragment of brachial valve preserving the front portion and the 
ends of the median septa shows the middle septum to be highest and longest of 
the 3 as usual in the genus. 
Measurements in mm.— 
Brachial Mid- Hinge Thick- 
Length length width width ness Height 
Holotype (pedicle valve)............ 11.9 ? 17.7 16.97” F 4.2 
Paratype ( “ Ss osp Roggab 4 Li, 10.8 r iy ees ? ? ? 
ff @ Sir mmodo2t)}. alst 7.7 ? 12.9 14.4 ? ? 
Types.—Holotype: 110992a; figured paratype: 110992d ; unfigured paratypes: 
110992b,c,e-f. 
Horizon and locality—Wells formation in Tennessee: Along the railroad, 
14 miles southwest of Cumberland City, Wells Creek Basin, Stewart County. 
Discussion.—This species is proportionately wider and less convex than E. al- 
ternata which it approaches in size although it never attains the large dimen- 
sions of the Oranda and Salona species. The zones of fine costellae in the Ten- 
nessee species are less wide, and many more of the strong costellae appear in 
the ornamentation of EF. foerstet. 
EOPLECTODONTA ? TRIRADIATA (Butts) 
Plate 203, B, figures 16-20 
Sowerbyella rugosa triradiata Butts, Virginia Geol. Surv. Bull. 52, pt. 2, p. 113, pl. 96, 
fig. 9, 1042. 
Shell small, somewhat trapezoidal in outline; the hinge forming the widest 
part; sides gently oblique; anterolateral extremities narrowly rounded; anterior 
margin straight. Surface marked by costellae of unequal size, 3 of which are 
more prominent than the others: 1 is median and the other 2 extend from the 
beak to the anterolateral extremities. Space between large costellae filled by a 
mat of finer costellae of 2 or 3 sizes. 
Pedicle valve unevenly and narrowly convex in lateral profile, the posterior 
half convex, the anterior half flattened and the place of geniculation narrowly 
convex ; anterior profile subrectangular, the median part nearly flat but the sides 
short and descending steeply. Umbo and beak small; region posterior to angle 
of geniculation gently convex; angle of geniculation about 85° ; region posterior 
to angle shorter than the trail ; anterior slope of trail long and steep; trail broadly 
sulcate in the median region; sides steep and set off from the trail by narrowly 
rounded anterolateral folds. Interarea long, apsacline. 
Brachial valve and interiors not known. 
Measurements in mm.— 
Hinge 
Length Midwidth width Thickness Height Surface 
PABIGEY DE As ac} nptoteultns * « 5.5 9.8 II.0 ? 1.4 5.8 
Hypotype (123257a).... 6.6 9.1 9.5 ? 2.9 9.5 
Types.—Holotype: 97582b; paratypes: 97582a,c; figured hypotype: 123257a. 
