31 
from the head of Frobisher bay, Baffin island, which Schuchert (1900) 
regarded as Trenton. C. canadensis is included in this material. Schuchert 
made his correlation on the maximum number of species referable to a 
single horizon. But the material was not collected from in situ. Schuchert 
writes (1900, 175): 
“ The BaflBn Land fauna has an early introduction of Upper Silurian genera in 
the corals Halysites, Lyellia, and Plasmopora. In Manitoba similar conditions occur 
in the presence of Halysites, Favosites, and Diphyphyllum. Other Upper Silurian 
types do not appear to be present This fauna shows an intimate relationship 
with that of the Galena of Minnesota, Iowa, and Wisconsin. Fifty-seven per cent 
of the species of Baffin Land also occurs in the Galena of the region just mentioned.” 
Schuchert was of the opinion that the fauna represented by the few 
fossils brought by Bell (1897) from Akpatok island “ connects directly 
with that of Silliman's Fossil Mount” (Baffin island). Whiteaves (1899, 
433-4), who described this fauna, considered it “remarkably similar to 
the fossils of the Trenton formation of the Red River valley in Manitoba,” 
which Schuchert accepted. It has been shown above that part of the 
“ Trenton ” of Red River valley is probably Richmond. But Ulrich (in 
Willis, 1912, 217) thinks this Baffin Island fauna is of Upper Black River 
age. Foerste (1928) described some cephalopoda collected from Putnam 
highland (probably from somewhere about longitude 74 degrees west), 
farther w'est in Baffin island, and compared them with the Red River fauna. 
Unfortunately the relation between the Lower Palaeozoic rocks developed 
in East and West Baffin island has not been wmrked out yet. Miss A. E. 
Wilson (1931, 187, 188, and in Soper 1928, 125) records the occurrence of 
“ C. anticostiensis ” and “ C. borealis ” in the drift near Amadjuak lake. 
This development is most probably connected with that of Putnam high- 
land. 
The difficulty in estimating the validity of Schuchert’s correlation lies 
in the fact that the fossils were collected from scree and may belong to more 
than one horizon. Bassler (1911, 36) has noticed this and concludes that 
“ the geologic section at Baffin Land consists of Black River strata resting 
upon the old crystalline rocks, followed by an early Trenton formation 
equivalent to the Stewartville and Prosser Limestones of Minnesota, and 
this in turn succeeded unconformably by the widespread coral zone of the 
Richmond Group.” Professor Schuchert (personal communication, 1935) 
tells me that “ for many years I have believed that many of the fossils I 
described or listed from Silliman's mount are really of Richmond time.” 
The age of this eastern Baffin Island fauna is important because certain 
small arctic collections have been compared with it. The fossils collected 
by Schei from Norman Lockyer island, Ellesmere island, are considered by 
Holtedahl (1913, 11, and 1917) to be “of the same age as the bulk of the 
forms described by Schuchert.” These include C. canadensis, which on 
inspection proves to be var. anticostiensis. This variety (= C. anticos- 
tiensis Bill.) is otherwise unrecorded from strata lower than the top of the 
Trenton. The Streptelasma comiculum recorded by Holtedahl (1913) from 
the same collection proves not to be this species, but a new species of 
Holophragrna. This materially weakens the Trenton correlation. 
The remaining occurrences of Calapoecia in the Arctic regions cannot 
be related to any definite horizon at present. Whitfield's (1900) con- 
