PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 569 
Types.—Holotype: 117134; figured paratypes: 98192a,b; figured specimen: 
117135. 
Horizon and locahty.—Whistle Creek formation on Lexington (15’) Quad- 
rangle, Virginia: On U. S. Highway 60, 100 yards southeast of Whistle Creek ; 
2 miles northwest of Lexington. 
Discussion.—Characterized by globular profile and presence of 3 to 4 costae 
in the sulcus. Compared with C. plicata, which occasionally develops tricostate 
forms, this species proves to be wider and more globular. It also differs from 
C. quadriplicata Willard in possessing a more rounded profile and in having less 
numerous costae on the flanks. Camerella globularis also resembles C. elliptica 
but differs in its more convex profiles and the seminude exterior. Camerella 
globularis shows considerable variation in the number of costae present in the 
sulcus and on the fold. One specimen has a single costa in the sulcus, and others 
have from 2 to 4. The two higher figures seem to represent the normal condition. 
CAMERELLA GREGERI Cooper, new species 
Plate 113, D, figures 20-31 
Shell large for the genus, slightly wider than long and having a pentagonal 
outline. Beak slightly greater than a right angle, anterolateral extremities nar- 
rowly rounded, anterior margin truncated. Greatest width anterior to the mid- 
dle. Surface smooth in the posterior half, but marked by subangular and com- 
pressed costae with interspaces about as wide as the costae, 5 to 7 costae on the 
fold, 4 to 6 in the sulcus, and 5 to 6 on the flanks. 
Pedicle valve slightly convex in lateral profile with the greatest convexity just 
anterior to the umbonal region. Sulcus originating at the middle, deepening 
abruptly and occupying one-half to two-thirds the width at the front. Tongue 
moderately long with a truncated extremity. Flanks gently convex and with 
gentle slopes to the margins. Spondylium wide and deep, septum reaching 
anterior to the middle. 
Brachial valve about twice as deep as the pedicle valve, only moderately con- 
vex in lateral profile but strongly arched in anterior profile. Fold originating at 
the middle, truncated at the front and moderately elevated. Flanks rounded and 
with steep slopes. Umbonal region strongly convex. Cruralium small. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
EROGVE cc ce cat ics. ons 3 17.8 17.6 19.1 4.7 14.5 
Parauype '( E8195) ew 2 17.2 16.8 17.8 3.8 12.8 
Types.—Holotype: 111126; figured paratypes: 111125, 117136a,c; unfigured 
paratype: 117136b. 
Horizon and locality —Plattin group (Macy formation) in Missouri near 
Glencoe, St. Louis County: Rockwoods Reservation, 20 miles west of Grover, 
St. Louis County; on Fredericktown road 5 miles southwest of Ste. Genevieve, 
Weingarten (15’) Quadrangle. 
