1915] PALAEOZOIC FossILs FROM Hupson Bay. 29 
Trenton limestone of Wisconsin. If our specimen were more perfect, 
its reference to this species might be justified. Assuming a slight defor- 
mation whereby the annulations have been rendered oblique, our 
form might be compared with Orthoceras olorus baffinensis, Schuchert, 
from the Trenton of Baffin Land. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 332 S. Royal Ontario Museum of Palaeontology. 
MELOCERAS, sp. indet. 
Plate II, Figure 5. 
Two fragments of a rather rapidly tapering, laterally compressed 
cyrtocone. The curvature is slight and the form is apparently exo- 
gastric. The fragments are about 60 mm. long and show a greater 
(dorso-ventral) diameter of 32 mm. at the anterior, and 23 mm. at the 
posterior end. 
Nine camerz are shown with a gradually decreasing width towards 
the posterior. On the convex side the first camera has a width of 6 mm. 
and the ninth a width of 3.5 mm. The sutures arch strongly forward 
on the siphonal (convex) side. 
The rather slight curvature and the lateral compression of the shell 
suggest the genus Meloceras as emended by Foord. Oncoceras articum, 
Schuchert, from the Trenton of Baffin Land, appears to be a related 
form, but I cannot regard our specimen as of that species. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 328 S. Royal Ontario Museum of Palaeontology. 
POTERIOCERAS TYRRELLI, Parks. 
Plate II, Figure 2. 
POTERIOCERAS TYRRELLI, Parks. Bur. of Mines of Ont., 22nd Rep., pt. I, p. 191, 1913. 
The species is founded on two specimens from the lower rapids of 
the Shamattawa river and on a photograph taken by Mr. Tyrrell of a 
third specimen of which he was unable to obtain possession. 
The best preserved specimen from which the accompanying drawing 
was chiefly made shows a cast of the chamber of habitation and of 
nine air chambers. The whole shell is sac-shaped with a slightly greater 
convexity of the siphonal or ventral side: the shell is therefore to be 
described as exogastric. The transverse section is ovate and slightly 
compressed on the ventral side. The maximum diameter is at the 
