PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 277 
apex, the slender pedicle groove and the posterior position of the apex in the 
brachial valve. This is a combination of characters not seen in any of the other 
species in the Appalachians. 
Genus SCHIZOTRETA Kutorga, 1848 
Schizotreta Kutorca, Verhandl. Russ.-Kais. Min. Ges. St. Petersburg for 1847, pp. 260, 272, 
pl. 7, fig. 6, 1848.—H att and Crarke, Pal. New York, vol. 8, pt. 1, p. 135, 1892.—Girry, 
Journ. Washington Acad. Sci., vol. 18, No. 5, pp. 128-142, 1928. 
Acrosaccus WIitLarD, Bull. Mus. Comp. Zool., Harvard Coll., vol. 68, No. 6, p. 258, 1928. 
The name Schizotreta is applied to brachiopods having a subconical pedicle 
valve and a brachial valve that is nearly flat or even somewhat concave. Kutorga’s 
type species, Orbicula elliptica, is a small shell having a nearly flat brachial valve. 
Furthermore, the brachial valve has the beak situated in a position distinctly 
posterior to the middle. The beak is not marginal, but in the type species and 
in all the American specimens here referred to this genus the beak is located 
in a submarginal position, often less than a millimeter anterior to the margin. 
Specimens of Dr. Willard’s genus Acrosaccus have the same characters as 
those of Schizotreta. Willard’s genus was created for shells supposed to be re- 
lated to Acrothele but without or rarely with a false cardinal area in the pedicle 
valve and with the brachial protegulum near the posterior margin. Although 
the type specimens do not show the pedicle opening it is stated that the presence 
of a “pedicle tube proved the relationship to the Acrotretacea rather than the 
Discinacea.” Actually the pedicle aperture in the numerous specimens now 
available is quite discinoid, and Acrosaccus proves to be a synonym of Schizotreta. 
SCHIZOTRETA CANADENSIS Wilson 
Schizotreta canadensis Witson, Geol. Surv. Canada, Bull. 8, p. 25, pl. 2, figs. 14, 15, 1946. 
Types.—Holotype: G.S.C. 6373; paratype: G.S.C. 6373a. 
Horizon and locality—Leray-Chaumont formation, in Ontario, Canada: Lot 
2, Concession IV, Cumberland Township. 
SCHIZOTRETA CORRUGATA Cooper, new species 
Plate 21, C, figures 7-20; plate 28, G, figures 24-28 
Shell of about medium size for the genus, longer than wide, depressed conical 
in profile and marked on the exterior by strong, elevated concentric ridges. 
Pedicle valve forming a depressed, asymmetrical cone; posterior slope steep, 
short, flat in profile; anterior slope nearly 3 times the length of the posterior 
slope, almost flat or slightly concave in lateral profile; apical angle greater than 
a right angle. Lateral slopes flat and fairly steep. Pedicle groove about 1.5 mm. 
long, moderately wide; foramen generally small. 
Brachial valve roundly elliptical in outline, the length being slightly greater 
than the width; beak small, smooth, located 4 mm. or less from the posterior 
margin ; posterior slope steep; anterior slope very gently convex; anterior pro- 
file gently convex. Ornamentation variable, often extreme; ridges variable in 
