8 
MUSEUM BULLETIN NO. 17. 
Other Northern Occurrences Related to the Black 
River-Trenton Formations of Lake Timiskaming. 
Receptaculites oweni Hall ? and Rhynchotrema ineequivalve 
(Castelnau) ? from the Trenton of Chief island assist us in cor- 
relating these beds with some other northern Ordovician occur- 
rences. Likewise Maclurea ( Maclurina ) manitobensis Whit- 
eaves, which appears to be closely related to Maclurea logani 
Salter, of the Lake Timiskaming occurrences, is found at several 
northern localities. Receptaculites oweni and Maclurea mani- 
tobensis are found in the Galena-Trenton formations in the Lake 
Winnipeg 1 region, and also at Silliman’s Fossil Mount, Fro- 
bisher bay, Baffin island. 2 Maclurea , probably M. manitobensis , 
is reported 8 from one horizon of the Port Clarence limestone 
as found on the Don river of Alaska, and M. manitobensis is 
definitely reported from limestones of the Lower Ramparts 4 of 
the Porcupine river of Alaska, and again along the 141st meri- 
dian between the Black and Porcupine rivers. 5 
Considering the small number of well established records 
of Black River and Trenton rocks in northern North America, 
each new discovery is of especial interest. The Lake Timis- 
kaming occurrence furnishes additional evidence of the once 
broad extent of these lower Ordovician strata, and indicates 
that their preservation has been due to protection from erosion, 
in this case at least, partly resulting from down-faulting. 
iWhiteaves, J. F. f Geological Survey of Canada, Palaeozoic Fossils, Vol. Ill, Part III. 
*Schu chert, Chas., Proc. U.S. National Museum, VoL XXII, 1900, p. 149. 
Utindle E, M., Am. Jour, of Science, Fourth Series, Vol. XXXII, 1911, p. 342. 
*Kindle, E. M„ Bull. Geol. Soc. Am.. Vol. 19, 1908, p. 323. 
*Cairnes, D. D., Geol. Surv., Can., Summ. Rcpt., 1911, p. 28. 
