1006 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Genus and species undet. 
Plate 99, C, figure 19; plate 148, A, figures 1-4; plate 217, D, figures 6, 7 
Several specimens consisting of four pedicle valves and a possible brachial 
valve having impunctate shell substance are considered to belong to an unde- 
scribed genus. The shells attain a width of about an inch and have a straight 
hinge wider or less wide than the midwidth. The pedicle valve has a moderately 
long interarea with a very narrow delthyrium and narrowly convex pseudodel- 
tidium. The interior of the pedicle valve is especially characterized by dental 
plates so close together that they form an unusually narrow delthyrial cavity. 
The exterior is marked by fine costellae and a moderately deep sulcus that origi- 
nates just posterior to the middle and produces a short tongue. 
The brachial valve tentatively assigned here and found in association with one 
of the pedicle valves is ornamented like the pedicle valve but is also sulcate and 
apparently has a short tongue. Bisulcate shells are not common. Consequently, 
it is unwise to make a genus on these shells until the brachial and pedicle valve 
can be definitely matched. The interior of this valve is marked by 2 long and 
parallel brachiophore plates which bound a deep and narrow notothyrial cavity. 
In this cavity is a short but stout cardinal process. The internal impression sug- 
gests a long and flattish brachiophore. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
Pedicle valve (117068b)...... T.3 ? 14.2 15.8 ? ? 
: * (1717066)... T2\2ds 19.3 ? 25.0 21.5 2 4.0 
Brachial valve (117068a)..... ? 12.7 19.8 20.0 ? 2.0? 
Figured specimens.—117066, 117067, 117068a,b. 
Horizon and locality.—Arline formation (middle) in Tennessee: On the north 
side of the old road in glade, 4 mile southeast of Friendsville, Concord (T.V.A. 
138-SW) Quadrangle. 
Base of Athens formation in Tennessee: Above the quarry 1 mile northeast 
of the courthouse in Athens, Athens (T.V.A. 125-NE) Quadrangle; 24 miles 
south-southeast of Riceville, Calhoun (T.V.A. 125-SW) Quadrangle. 
Pratt Ferry formation in Alabama: 0.2 mile southeast of Pratt Ferry, Blocton 
(15’) Quadrangle. 
Discussion —The interior details of each of the valves described above are 
unlike any other known genus, but until the valves can be definitely established 
as belonging together it is unwise to create a genus for them. 
