PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 551 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
EIGLORY Pel secstteaitiercieri ses ss 16.7 15.3 21.8 16.9 10.8 
Paratype; shes isi. besa 15.7 15.2 20.0 13.0 11.7 
Types.—Holotype: 117115a; figured paratype: 117115b. 
Horizon and locality —Eureka group (upper part of dark gray shale under the 
Eureka quartzite) in Nevada: On the north-facing nose of hill 8167 on Martins 
Ridge, Monitor Range, Roberts Mountains (1°) Quadrangle. 
Discussion—This is the largest of the species so far found in the Roberts 
Mountains area. It is characterized by moderately strong costellae, a moderately 
widely elliptical outline, and fairly strongly elevated fold and deep sulcus. Com- 
parison with O. multicostellata of the Appalachians is made under the descrip- 
tion of that species. The Nevada form is suggestive of O. simulatrix and occupies 
a similar stratigraphic niche. It differs from that species, however, in having a 
narrower fold and sulcus, and finer costellae. 
OXOPLECIA OCCIDENTALIS (Butts) 
Plate 101, C, figures 16-22 
Cliftonia occidentalis Burts, Alabama Geol. Surv., Special Rep. 14, p. 126, pl. 31, figs. 21, 22, 
1926. 
The type lot consists of three specimens, one of which (71529c) is a young 
distorted pedicle valve too poor for description. The remaining two are a young 
pedicle valve and an adult brachial valve. The former is nearly circular in out- 
line but with the width slightly greater than the length. The sulcus originates 
slightly more than one-third the length anterior to the beak, is shallow through- 
out its length. At the front margin the sulcus occupies about one-third the width 
of the valve. Flanks flattened, with moderately steep slopes to the margins. Um- 
bonal region strongly convex in profile with strongly incurved beak. Sulcus with 
5 costellae, flanks with 14 costellae. 
Brachial valve slightly wider than long, gently convex in lateral profile but 
with a narrowly convex umbo. Fold originating just anterior to the umbo, 
slightly elevated at the front margin, and occupied by 7 costellae. Flanks con- 
vex, with steep slopes to form a narrowly rounded shell in anterior profile. 
Flanks with 14 costellae. Beak low, not protruding beyond the posterior margin. 
Measurements in mm.— 
Length Width Thickness 
Lectotype (brachial valve)................. 16.0 17.2 6.6 
Paratype (pedicle valve 71529b)............ 12.5 14.6 3.9 
Types.—Lectotype: 71529a; paratypes: 71529b,c; figured hypotypes: 
117116a,b. 
Horizon and locality.—The published locality of this species is “Basal Chicka- 
mauga limestone, probably Ridley horizon, old quarry half a mile northeast of 
Gate City,” Ala. This is evidently an error because a label in Dr. Butts’ hand- 
writing with other Alabama specimens reads “14 miles northwest of Swansea 
