PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 641 
ROSTRICELLULA MISSOURIENSIS (Fenton and Fenton) 
Plate 135, B, figures 8-10 
Rhynchotrema missouriense FENTON and Fenton, Proc. Iowa Acad. Sci. for 1922, vol. 20, 
p. 73, pl. 2, figs. 22-26, 1924. 
Figured specimen.—111488. 
Horizon and locality—Barnhart (or Macy) formation in Weingarten (15’) 
Quadrangle, Missouri: 24 miles west of Ste. Genevieve; 14 miles north of Chi- 
cago Summer School Camp. 
ROSTRICELLULA MULTICOSTATA Cooper, new species 
Plate 139, D, figures 37-53 
Shell of about medium size for the genus, slightly wider than long; apical 
angle about 100°; sides narrowly rounded; anterior margin gently and broadly 
rounded. Costate, 4 to 8 costae in the sulcus, 5 to 9 on the fold, and 11 on the 
flanks. 
Pedicle valve gently convex in lateral profile and with the greatest convexity 
at the umbo; anterior profile broadly and gently convex; sulcus originating 2 to 
3 mm. anterior to the beak; sulcus broad and shallow throughout ; tongue short, 
broadly rounded. Umbo strongly swollen; beak strongly curved and overhang- 
ing the brachial umbo. Flanks narrow, gently convex and with steep slopes. 
Brachial valve fairly strongly convex in lateral profile and with the maximum 
convexity at the middle; anterior profile strongly and broadly convex; fold origi- 
nating at or near the middle, low throughout its extent; umbonal and median 
regions inflated ; flanks swollen and with steep slopes. 
Measurements in mm.— 
Brachial 
Length length Width Thickness 
TVG 5 ML es er 11.3 10.0 12.4 7.6 
Pasaty pe GIIZAAED) it on, dbs ceil ht 0.7 8.6 10.7 Vf 
- (Gat 75 ee ee 10.0 8.7 10.2 Ge 
USAT was S yigsls sare oa 10.1 9.0 9.6 6.7 
3 CEN O2IE) Soe tk oe oe 9.2 8.0 10.2 6.6 
e CE QBTEy CANIS VN GA 8.7 7.7 9.6 6.6 
‘ (aigoone io: Sees. ova Be 6.8 6.2 7.4 4.8 
# GRIF A2TE Viesie’ surctepon S8e 6.1 5.5 6.8 4.1 
Types.—Holotype: 1172214; figured paratypes: 11722Ic,e; unfigured para- 
types : 117221b,d,f-i. 
Horizon and locahty.—Ellett formation, calcarenite 10 feet above the Knox 
in Virginia: Slope on west side Virginia County Highway 615, 1 mile south of 
Ellett, Blacksburg (15’) Quadrangle. 
Discussion.—This species is suggestive of R. plena (Hall) but is uniformly 
smaller in size than that species and is a more rotund form. It differs from other 
species seen at the base of the Lenoir in its larger size and more numerous costae. 
