698 STUART WELLER 
near James Bay (XIV), and another along the western shore ot 
Hudson Bay (XV). In all these regions the general Silurian 
fauna of America and Europe has been identified. The strata lie 
directly upon pre-Cambrian crystalline rocks, and as they could 
not have been deposited in these isolated patches, they must 
represent the remnants of a Silurian sheet which was at one 
time continuous and covered the entire intermediate region. 
Silurian strata have been recognized still further north on the 
islands at the mouth of Hudson Bay (XVI), and on the islands 
and mainland round about the Gulf of Boothia (XVII) and west 
of the Boothia peninsula (XVIII). In these two latter regions 
Silurian fossils have been found in abundance by several of the 
Arctic expeditions. From this general area Dawson’ gives a list 
of thirteen localities from which Silurian fossils have been col- 
lected. Ifthe region could be visited and properly studied, a 
prolific fauna would doubtless be secured. West of McClintook 
Channel the Silurian has not been properly differentiated from 
the Devonian, and Silurian fossils have not yet been found. In 
northern Greenland and in Grinnell Land (XX) Silurian strata 
with their characteristic fauna are known to exist. 
Turning now to the map of the north polar regions (Fig. 2), it 
will be seen that the distance between northern Greenland (XX) 
and northern Russia (XXIII) where the Silurian fauna is known, 
is not extreme. At very near the halfway point between, lies 
Spitzbergen (XXI). The shores of these islands are known to 
consist for the most part of Paleozoic strata, and, although no 
Silurian rocks have yet been recorded from the islands, the pres- 
ence of the Paleozoic strata isa connecting link across this little 
known Arctic region. In western Russia (XXIV) the Silurian 
strata are not exposed, but the area colored is occupied by 
Paleozoic strata of younger age than the Silurian, and is possi- 
bly underlain by the Silurian. The area in Russia between the 
regions marked (XXIII) and (XXIV) is occupied by Mesozoic 
strata, and the Paleozoic beds with the Silurian among them, 
doubtless underlie the whole region. The island of Gotland in 
™ Ann. Rep. Geol. Sury. Canada, new series, Vol. II, p. 45 R. (1887). 
