576 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
less prominent, and the sulcus is shallower. This species is unlike any other de- 
scribed Marmor Camerella. It is larger than, and ornamented differently from, 
C. ventricosa of the Crown Point limestone. The fold and sulcus are wider and 
deeper in C. pennsylvanica than in the type specimen of C. varians. 
CAMERELLA PERPLEXA Cooper, new species 
Plate 115, A, figures 1-5; plate 115, B, figures 6-11 
Shell of fairly large size for the genus, length and width about equal; outline 
subpentagonal ; posterolateral extremities long and straight forming an angle of 
92°; sides narrowly rounded; anterolateral extremities short and oblique toward 
the middle; anterior truncate; anterior commissure broadly uniplicate; valves 
unequally convex, the brachial valve having the greater depth. Surface costate, 
in the anterior four-fifths ; umbonal region of both valves smooth; costae strong, 
angular, 4 on the fold, 3 in the sulcus, and 4 on the flanks. 
Pedicle valve gently convex in lateral profile; broadly and gently convex in 
anterior profile; umbo somewhat swollen; sulcus originating about 4 mm. an- 
terior to the beak, shallow in the median region but becoming deep at the anterior 
margin. Tongue only moderately geniculated, moderately long, and truncated. 
Flanks narrowly rounded and swollen and with steep lateral slopes. Beak mod- 
erately long. 
Brachial valve moderately convex in lateral profile but strongly and roundly 
domed in anterior profile. Umbo moderately convex; median region swollen; 
fold wide and fairly strongly elevated in its anterior third. Flanks swollen and 
with precipitous sides. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
1513) C0. 2 lm RE em reap 11.8-+ II.2 12.2 2.8 8.5 
Figured specimen ............. 12.8+ 11.6 13.1 3.5 9.0 
Type.—Holotype: 117143; figured specimen: I11123. 
Horizon and locality—Elway formation, in Tennessee: $ mile north of Eidson, 
Kyles Ford (T.V.A. 170-SE) Quadrangle. 
Same formation in Virginia: East of Moccasin Creek on Virginia County 
Highway 679, # mile south of Tumbez, Moll Creek (T.V.A. 196-SE) Quad- 
rangle. 
Discussion.—This species is characterized by its erect form, strongly defined 
costae, and the presence of 3 costae in the fold and 4 on the sulcus. It differs 
from C. globularis from the Whistle Creek formation in its less convex valves 
and more erect beak. It differs from C. multiplicata, also of the Elway forma- 
tion, in the less numerous costae and more robust shell. Its form is somewhat 
like C. quadriplicata, but it is not so robust and the details of the ornamentation 
are different. 
