34 
The question whether the Lyckholm and 5a, partly or entirely, are Silu- 
rian or not, has still to be left open.’’ But in his table (179) Troedsson 
correlates F 2 (the Borkholm) with the Clinton. This contradicts Twen- 
hofel’s conclusion, which, however, is upheld by Strand’s work on the 
cephalopods of the Gasteropod limestone (5a) of the Oslo region (1933, 
107). 
Jones (1928, 513) offered evidence, based on Sowerbyella and Leptel- 
loidea species, in favour of the conclusion made independently by Troeds- 
son. But he is of the opinion that such an horizon is unrepresented in 
America (1925, 387-8). Ulrich (1926, 347), however, differs from this 
view. Twenhofel (1928, 78, 80) has made direct comparisons of faunas 
and, although the number of species common to the two areas is not large, 
inclines to correlate the Caradocian and Ashgillian of the Haverfordwest 
district with the English Head and Vaureal; the Keisley limestone and that 
of the Chair of Kildare with the Vaureal and lower part of the Ellis Bay; 
the Haverford and Millin stages with the upper division of the Gun River 
and the lower division of the Jupiter formation. This is important, for 
difficulty in correlation between Europe and America is increased by the 
individual fossil nomenclature of each continent. 
Siberia. C. cribrijormis ” from the banks of the Middle Tunguska 
(presumably the Steiniger Tunguska river of Stieler 1930-1, Map 68) is 
recorded by Lindstrom (1882^, 12-13). The fossils collected with it were 
loose and apparently at least two horizons are represented. The lower 
of these, in the presence of “ Calapoeda cribrijormis Nich.”, Columnaria 
alveolata Goldj., and Plasmopora affinis (Bill.), was regarded as equivalent 
probably to the “ Lfeptaena-limestone ” of Dalecarlia and the “ Hudson 
River group” (10). Lindstrom compared the Siberian specimen with 
material sent to him by Nicholson, so it is almost certainly C. canadensis, 
as understood here. Plasmopora affinis (Bill.), now Lyellia affinis (Bill.), 
ranges in Anticosti strata from stage 4 of the Ellis Bay to the Chicotte 
formation; Columnaria alveolata is seen earliest in stage 4 of the Vaureal. 
OCCURRENCES IN STRATA OP BLACK RIVER AGE 
The type of C. canadensis came from the “ Black River limestone, near 
Ottawa ” (Billings 1865) . It has also been recorded from Little Chau- 
di^re, Ottawa river, Mechanicsville (Ami, 1902, 714) and “ North End of 
lake Huron, province of Quebec, and on Anticosti ” Foerste (1903). Lambe 
(1899, 44) gives the following Black River localities for C. canadensis: 
Hull (Ottawa); Paquette rapids, Ottawa river; near point Blue, lake 
St. John, Que. Foerste (1932, 56) found a specimen in the upper part of the 
Black River formation exposed on Cloche island, in the north part of lake 
Huron. 
Bassler (1915, 154) remarks that it is “possible that the types of C. 
canadensis were derived from the Richmond and not from the Black River.” 
The writer has been unable to confirm this; nor is he aware that a revision 
has been made of the fauna from Paquette rapids listed by Ami (1896, 153) 
and referred to the Birdseye and Black River. ^ He has not been able to 
1 Since the specimens of G. canadensis sent to me as topotypea by the Geological Sur- 
vey, Canada, came from Paquette rapids, this should be Billings’ type locality. I have 
not yet confirmed this. 
