1915] PALAEOZOIC FOssILS FROM Hupson Bay. 19 
This form must be compared with H. borealis, listed by Ami but 
without description in ‘‘The Cruise of the Neptune”’. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 361 S. Royal Ontario Museum of Palaeontology. 
TROCHONEMA UMBILICATUM, Hall sp. 
PLEUROTOMARIA UMBILICATUM, Hall. Pal. New York, Vol. I, pp. 43 and 175, 1847. 
TROCHONEMA UMBILICATA, Salter. Geol. Sur. Can., Can. Org. Remains, Dec. I, p. 27, 
pl. VI, fig. 3, 1859. 
TROCHONEMA UMBILICATUM, Ulrich. Geol. Sur. Minn., Palaeon., Vol. III, pt. II, p. 1047, 
pl. LX XVII, figs. 1-8, 1897. 
Seven specimens, all casts, showing some variation. They are ascribed 
to this species with considerable certainty. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 360 S. Royal Ontario Museum of Palaeontology. 
MACLUREA SUBOVATA, Parks. (nom. prov.) 
Plate VII, Figures 4 and 5. 
MACLUREA SUBOVATA, Parks. Bur. Mines of Ont., 22nd Rep., pt. I, p. 190, 1913. 
It is with considerable hesitation that a new species is established 
for this Maclurea which is represented in the collection by one good 
cast and several fragments. It cannot be denied that the specimens 
show considerable resemblance to M. logani, Salter, and to M. bigsby1, 
Hall. After careful comparison, however, I am unable to ascribe the 
forms with any certainty to the species mentioned, and until better 
material is secured I am of the opinion that the specimens are worthy of 
a provisional name. 
The most perfect specimen, which I think is nearly complete, although 
the aperture is not shown, measures about 65 mm. in maximum diameter. 
Only two distinct whorls are seen, but there is evidence of a third very 
small initial whorl. The shell is thick and partly worn away on the 
under (flat) surface, but judging from the cast of the interior, the most 
striking peculiarity is the considerable convexity shown by the under 
surface of the whorls.’ The outer side of the volutions is characterised 
by a rather straight outline which is more pronounced towards the 
aperture. The umbilicus is about 15 mm. in diameter. The measure- 
ments of the outer whorl nearest the aperture are as follows: Maximum 
1 Following Ulrich, the flat side is regarded as the base; the ‘‘umbilicus”’ therefore 
is really an inverted spire. 
