62 
This fauna is from a single small outcrop and represents the only 
collection from rocks of this age on Great Slave lake. On the fossil 
evidence the conclusion seems justified that this locally is a link in the 
connexion between the Arctic and the great Interior Guelph Sea. 
DESCRIPTION OF SPECIES 
Receptaculiies sp. 
Plate XII 
Only a fragment is known. It is a flattened and expanded form 
which bears the closest resemblance to R. oweni of any described species. 
The cells of the disk are small at the central point and diverge concen- 
trically into larger ones toward the margin. Preserved in red, arenaceous 
limestone so that only the form and general characters are definitely 
determinable. 
Locality and Horizon . North arm, Great Slave lake, North West 
Territories. Ordovician. 
Camarotoechia sp. 
Plate XIII, figures la-d 
Medium sized, length in the best preserved specimen 20 mms. and 
greatest width 22 mms. Ventral valve with prominent umbo and sharp 
beak which projects over the dorsal valve. Median sinus extending 
two-thirds of the distance from the anterior margin toward the beak. 
Dorsal valve more convex than the ventral valve. Surface covered with 
plications, of which there are three in the sinus and four on the fold. On 
each side of the sinus seven plications can be distinguished, although they 
become progressively less distinct the farther they are removed from the 
more median ones. The plications are not very distinct over the umbonal 
part of the shell. Imbricated concentric lamellae over the plications. 
One specimen is peculiar in that one plication on the fold is suppressed 
so that only three are well developed; the fourth is evident, though in the 
alternate arrangement with those on the sinus at the anterior margin. 
Most of the specimens are preserved in dolomitic limestone and consequently 
only in those best preserved does the concentric lamellae show. 
Occurs in dolomitic limestone that outcrops in the vicinity of one 
of the former sites of Rae. 
Locality and Horizon. North arm, Great Slave lake, North West 
Territories. Ordovician. 
