of the Paleozoic Outlier of Lake Timiskaming. 308 



pletely covered by younger deposits, this supposition 

 could not be established. 



Silurian: Wabi formation, — The base of the Silurian 

 system, or of what is here called the Wabi formation, is 

 nowhere exposed in the Timiskaming area. The lowest 

 strata are green shales with thin layers of limestone that 

 contain a great many ostracods, particularly Leperditia 

 hisingeri fabulina, after which the zone has been named. 

 Higher up, these shales grade into thin-bedded magnesian 

 limestones, the whole thickness of this formation being 

 about 120 feet. In the limestone beds there is one horizon 

 that contains a great many small Hormotomas, and con- 

 sequently the upper limestone member has been desig- 

 nated the Hormotoma zone. Fossils are not plentiful in 

 this formation, but among the most characteristic are: 

 Leperditia hisingeri fabulina, L. hisingeri, L. arctica, Zy- 

 gobolbina williamsi, Hormotoma sp., Pterinea cf. brisa, 

 P. elegans, P. occidentalis, Camarotoechia? winiskensis, 

 Rhynchospira lowi, and a number of other long-ranging 

 brachiopods. 



In other areas where a fauna similar to this has been 

 found, Virgiana decussata occurs below the Leperditia 

 hisingeri fabulina zone. In the Timiskaming area, the L, 

 hisingeri fabulina zone is almost at the base of the ex- 

 posed part of the section, and if the Virgiana decussata 

 zone is present, it is in the unknown interval previously 

 described. 



A fauna similar to that of the "Wabi formation occurs in 

 the Port Nelson and Severn River limestones of Hudson 

 bay (Savage and Van Tuyl 1919), and undoubtedly these 

 strata are of equivalent age. In the Lake Timiskaming 

 district, there are fewer species, although this may be due 

 to the fact that exposures of the formation are not of 

 great extent and the collecting places are very limited. 



Savage and Van Tuyl (1919) have correlated rocks of 

 this age in the Hudson Bay region with the lower part of 

 the Stonewall formation of Manitoba and with rocks of 

 equivalent age in eastern Wisconsin (the upper part of 

 the Mayville limestone), and the northern peninsula of 

 Michigan. In the Dyer Bay dolomite of the Lake Huron 

 district, Zygobolbina williamsi was first found (Williams 

 1919). This is perhaps the only diagnostic fossil so far 

 known common to the Wabi formation and to the Cataract 

 of southern Ontario. If the strata in which this ostracod 



