1915] PALAEOzOIC FossILs FROM HupsoN Bay. 61 
EUOMPHALUS ROTUNDUS, sp. nov. 
Plate VII, Figures 6 and 7. 
This species is represented by two imperfect specimens, one showing 
a mould of the base and portions of the internal casts of the lower whorls 
and the other showing a mould of the apical side with parts of the shell 
adhering to the matrix. In addition are several fragments, probably 
referable to this species. 
The maximum diameter of the larger shell is about 85 mm. The 
coiling is discoidal with three volutions. The umbilicus is wide open 
and about 18 mm. deep. On the apical side, the central point is depressed 
7 mm. below the line joining the upper surfaces of the opposite sides 
of the body whorl. In Plate VII, Figure 7, this depression does not 
appear as great, but this is owing to the absence of the shell, which is 
much thicker (3 mm.) on the body whorl than on the small whorls near 
the centre. The whorls are almost circular in the cast, having a lateral 
diameter of 24 mm. and a vertical diameter of 23 mm. at a point con- 
venient for measurement. The apical portion of the whorls is filled 
with a white, organically deposited calcite arranged in convex dia- 
phragms simulating the septa of a cephalopod. Neither of the shells 
show the slightest evidence of the surface characteristics, and there is 
no trace of a peripheral alation; in fact, the shape of the whorl is a 
reasonable basis for the assumption that such structures were not pre- 
sent. Some of the smaller pieces indicate that at least the inner sides 
of the whorls were marked by fine transverse lines of growth. Accept- 
ing Lindstrém’s description of Euomphalus there can be no doubt that 
our species falls within that genus.! 
Locality—Limestone rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
Nos. 348 and 349 S. Royal Ontario Museum of Palaeontology. 
EUOMPHALUS MINOR, sp. nov. 
Plate IV, Figures 8 and 9g. 
TREPOSPIRA Cf. KOKENI, Lindstrém, Parks. Bur. Mines of Ont., 22nd Rep., pt. I, p. 194, 
1913. 
This species is represented by a fragmentary mould of the exterior 
and by an internal cast which apparently belongs to the same species. 
The shell is about 8 mm. wide with a low depressed spire. Four whorls 
in all can be made out indistinctly. 
The mould shows a relatively large body whorl characterised by a 
gently rounded lateral aspect with a rather sharp carina in the superior 
1Sil. Gast. and Pter. of Gotland, p. 136. 
