IIo SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Mifflin member of Platteville formation—This name was proposed by C. A. 
Bays for 174 feet of thin-bedded limestone exposed on the Pecatonica River at 
Mifflin, Iowa County, Wis. This member underlies the Magnolia and overlies 
the Pecatonica members. No fossils are listed. 
Magnolia member of Platteville formation—This name is applied by Bays 
and Raasch (1935, p. 298) to the “Upper Buff” division of earlier authors. 
These are light-buff, moderately thick-bedded dolomites, thickest in south-central 
Wisconsin. 
Doleroides ottawanus Wilson ? S. plattinensis Fenton 
Obolellina dixonensis Cooper S. plattinensis crassa Raasch. 
Strophomena auburnensis impressa Raasch 
Templeton and Willman (1952, fig. 3) divide the Magnolia member into two 
formations which are themselves many times divided into members. The Grand 
Detour formation (with seven members) attains a thickness of slightly more 
than 50 feet of dolomite or limestone, thicker bedded than the Mifflin below. 
The Nachusa formation (of three members) is 19 feet thick, of dolomite or 
limestone, and containing Foerstephyllum and Tetradium. No brachiopods are 
recorded from either formation. 
Quimbys Mill member of Platteville formation——This name was proposed by 
Agnew and Heyl (1946, p. 1585) for the “Glass Rock” between the Spechts 
Ferry and the McGregor member of the Platteville formation. It consists of 
limestone and dolomite, 12 feet thick at the type section, at old Quimby’s Mill 
in SESSE4 sec. 11, T. 1 N., R. 1 E., near the Fever River at Etna, Wis. The 
formation abounds in Opikina. It is placed with the Spechts Ferry by Templeton 
and Willman (1952, fig. 3). 
Correlation of Platteville formation.—The Platteville formation abounds in 
Strophomena, Opikina, Pionodema, and Doleroides. The combination appears 
in the Chaumont and extends into the early Rockland. In the Appalachians this 
combination comes in with the Wardell and continues through the Lebanon. The 
writer, therefore, correlates the Platteville with Chaumont and part of the 
Rockland. 
Decorah formation.—This formation is composed chiefly of greenish shale 
with thin limestone layers. According to Kay (1935, p. 289) “Southward, the 
calcareous shales pass into limestones, of which the lower, the Guttenberg mem- 
ber, are gray with brown, ‘oil rock’ partings, and the upper, the Ion member, 
bluish, containing intercalated greenish, calcareous shales. Northward from the 
type locality, the members persist as greenish, calcareous shales.” Three mem- 
bers have been distinguished from the bottom up: Spechts Ferry, Guttenberg, 
and Ion. 
Spechts Ferry member of Decorah formation.—Blue or green laminated shale 
with a thickness from 5 to 8 feet from Platteville, Wis., to southern Minnesota. 
To the north it thickens to nearly 4o feet. In Minnesota it is the Stictoporella 
bed of the Minnesota Survey. The following brachiopods are reported: 
Crania halli Sardeson = Petrocrania halli (Sardeson) 
C. setigera Hall = Acanthocrania setigera (Hall) 
