PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 533 
cus swollen and with steep lateral slopes. Beak elongated, hinge narrow, pseudo- 
deltidium marked by characteristic median ridge. 
Brachial valve oval in outline with a moderately to strongly convex lateral 
profile ; anterior profile broadly and moderately convex and marked medially by 
a narrow fold; umbo swollen; median region inflated; fold narrowly rounded, 
low, barely perceptible at the umbo but becoming prominent at about the middle ; 
fold subcarinate in profile, separated from the swollen flanks by shallow, oblique 
grooves. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
FAEGEM EE Wc dttclattade cRIa tee bale aleve dine 00 a7 3.3 3.4 1.5 2.0 
Paratype (pedicle valve 117092c)..... 5.4 ? 5.3 ? 2.6 
rr (brachial valve 117092b).... ? 3.5 3.9 ? 2.0 
Types.—Holotype: 117092a; figured paratypes: 117092b,d; unfigured para- 
type: 117092c. 
Horizon and locality—Table Head series in Newfoundland: At Table Point 
Cove. 
Discussion—This species is characterized by its small size, its long, deep, and 
angular sulcus, and the prominent, long, narrowly rounded fold. This folding 
distinguishes the species from all others now described. 
ONYCHOPLECIA LONGIROSTRIS (Billings) 
Plate 100, A, figures 1-3 
Camarella longirostra BiLt1incs, Canadian Nat. Geol., vol. 4, p. 302, 1859; Geol. Canada, 
p. 127, fig. 53, 1863. 
Camarella ? longirostris Billings, TWENHOFEL and WHITING in Twenhofel, Geol. Soc. Amer. 
Special Pap. 11, pp. 30, 53, pl. 7, figs. 25-27, 1938. 
Shell of about usual size for the genus, tear-shaped in outline with an attenu- 
ate beak; lateral margins rounded; apical angle about 70° ? Anterior commis- 
sure broadly uniplicate. Surface smooth. 
Pedicle valve moderately convex in lateral profile and with the maximum con- 
vexity located just posterior to the sulcus; anterior profile broadly, moderately, 
and evenly convex; umbonal region flattened; median region moderately swol- 
len; sulcus confined to the anterior quarter, wide, shallow, and defined by a 
narrow, oblique fold on each side; sulcus in width equal to about half the shell 
width. Lateral regions somewhat swollen and with moderately steep slopes to 
the margins. Divergent dental plates visible at beak. 
Brachial valve subcircular in outline; lateral profile strongly convex ; anterior 
profile strongly convex; maximum convexity at the middle where the valve is 
strongly swollen; fold defined in the anterior quarter only, demarcated by shal- 
low oblique grooves; fold rounded. Lateral slopes steep. 
Measurements in mm.—Holotype, length 7.0 ?, brachial length 6.1, width 6.2, 
hinge width 2.8, thickness 3.5. 
Type.—Holotype: G.S.C. 1039. 
