986 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Genus PIONODEMA Foerste, 1912 
Pionodema Foerrste, Bull. Sci. Lab., Denison Univ., vol. 17, p. 139, 1912.—CoopPeEr, Journ, 
Paleont., vol. 4, pp. 369-382, 1930—SCHUCHERT and Cooper, Mem. Peabody Mus. Nat, 
Hist., vol. 4, pt. 1, pp. 141-142, 1932. 
PIONODEMA CAMERATA Cooper, new species 
Plate 162, E, figures 24-32 
Shell of moderate size for the genus, wider than long, subrectangular in out- 
line; widest at about the middle; hinge narrow; sides rounded; anterior gently 
rounded; surface marked by costellae that number 14 or 15 in 5 mm. at the 
front of an adult shell. 
Pedicle valve moderately convex in lateral profile, with the maximum curva- 
ture just anterior to the umbo and the anterior half somewhat flattened ; anterior 
profile broadly and fairly strongly convex ; median and umbonal regions swollen ; 
flanks moderately convex but with moderate slopes to the margin. Interior with 
large bilobed muscle area with somewhat elongate diductors and a long median 
ridge extending anteriorly from the adductor field; region on each side of muscle 
area marked by oblique, elongate ridges. 
Brachial valve with lateral profile slightly more convex than that of the pedicle 
valve and with the maximum convexity in the umbonal region. Anterior profile 
somewhat strongly domed. Umbonal and median regions strongly swollen; an- 
terior slope long and moderately steep. Flanks convex, and with short and steep 
slopes. Interior with brachiophore plates swinging anteriorly to meet and form 
a long V-shaped chamber. Cardinal process with long shaft and small lobate 
myophore. 
Measurements in mm.— 
Brachial Hinge 
Length length Midwidth width Thickness 
ie lellcls 7) ee ? 11.4 14.2 8.0 ? 3.6 ? 
Paratype (117343a)... 11.4 ? 14.5 10.2 2702 
if (1173434) 00.) 10.7 Hr.2 8.8 2.0? 
Types.—Holotype: 117343k; figured paratypes: 117343a-c,i,j,m,o; unfigured 
paratypes: d-h,l,n,p,q. 
Horizon and locality—Sevier formation (Bacon Bend member-top, just under 
Bays red beds) in Tennessee: 4 mile northeast of Fourmile Church, Tallassee 
(T.V.A. 139-SE) Quadrangle. 
Discussion—This species is characterized by moderately strong ornamenta- 
tion but more especially by the camerate arrangement of the brachiophore plates 
of the brachial valve. None of the specimens, which are all preserved as impres- 
sions of the interior or exterior, shows unequivocal traces of punctae. This made 
it difficult to decide whether the species belongs to Pionodema or Doleroides, 
because the brachial plates suggest the latter genus. It was decided that Piono- 
dema is the correct genus because of the character of the pedicle muscle area 
and the nature of the cardinal process. 
The pedicle muscle area is like that of Pionodema rather than Doleroides be- 
