26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
thick, with some magnesian and shaly limestone at the base. Fossils are rare 
but the following brachiopods are recorded: 
Rafinesquina cf. alternata (Emmons) = R. cf. R. trentonensis (Conrad) 
R. clara Okulitch = Opikina clara (Okulitch) 
R. minnesotensis Winchell = O. minnesotensis (N. H. Winchell) 
*Strophomena incurvata (Shepard) 
Strophomena sp. 
Zygospira recurvirostris (Hall) 
Presence of Crytophragmus and some other fossils suggests lower Lowville. 
Moore Hill formation.—Consists of about 20 feet of limestone containing 
“birdseyes” and in the lower part thin aphanitic beds and thin greenish layers. 
Tetradium celluloswm, Lambeophyllum, and Stromatocerium are common. The 
brachiopods recorded are: 
*Rafinesquina cf. alternata (Emmons) = R. cf. R. trentonensis (Conrad) 
R. clara Okulitch = Optkina clara (Okulitch) 
*R. minnesotensis (N. H. Winchell) = Opikina minnesotensis (N. H. Winchell) 
Rafinesquina n. sp. 
*Strophomena filitexta Hall 
Zygospira recurvirostris (Hall) 
Coboconk formation.—This formation consists of 20 feet of moderately 
heavy-bedded, aphanitic to fine-grained limestone, gray-brown to gray and 
weathering brown. The uppermost bed is of fine- to medium-grained limestone 
containing a fauna with some different species from those below. Cryptophrag- 
mus is present in the lower beds but Receptaculites occidentalis, Calapoecia cana- 
densis, Hesperothis tricenaria, and Maclurites logani occur in the top layer. 
Brachiopods are: 
Leptaena cf. radialis Okulitch = Cyphomena cf. C. radialis (Okulitch) 
Rafinesquina alternata (Conrad) = Rafinesquina trentonensis (Conrad) 
R. clara Okulitch = Opikina clara (Okulitch) 
R. minnesotensis (N. H. Winchell) = 0. minnesotensis (N. H. Winchell) 
Strophomena cf. corrugata Okulitch 
*S. filitexta Hall. (Identification doubtful.) 
Zygospira recurvirostris (Hall) 
According to Okulitch the lower beds have affinities with Chaumont but Kay 
(1937, p. 250) argues that the Coboconk is of Rockland age. Okulitch believes 
that the only Rockland elements occur in the uppermost bed as listed above. He 
believes further that the whole formation is correlative to Chaumont age be- 
cause the characteristic Rockland elements are missing. The only Rockland he 
will concede is the uppermost bed. On the chart the entire Coboconk is correlated 
with the Rockland. 
MANITOULIN ISLAND REGION 
Foerste (1912a, pp. 38-41) described the stratigraphy of Cloche Island and 
others of the Manitoulin Group and assigned ages to several of the beds. Kay 
(1937, pp. 257-259) discusses the same sequence but assigns the ages differently 
from Foerste. Two of the three formations were named by Foerste in ascending 
order: Lowville, Swift Current, and Cloche Island. 
