1915] PALAEOZOIC FOssILS FROM HupDSON Bay. 31 
DISCOCERAS (?) SHAMATTAWENSE, sp. nov. 
Plate I, Figure 1. 
TROCHOCERAS INSIGNE, Parks. Bur. Mines of Ont., 22nd Rep., pt. I, p. 192. 
The specimen consists of a well preserved mould of part of the 
exterior showing portions of four volutions. The whorls appear to be 
wound in a plane and to come in contact with each other without an 
impressed zone. The volutions increase very gradually in width and 
are ornamented with bold costz, most strongly developed on the inner 
side, passing almost directly outward and becoming fainter with an 
orad inflection near the outer margin of the whorl. The mould gives the 
impression that the venter was rather narrow. The outer volution is 
not quite complete, but is probably 22 mm. wide; the second volution 
has a width of 12 mm. and the third a width of 7 mm. The coste on 
the outer whorl are 5.5 mm. apart on the median line; on the second 
whorl they are 4 mm. apart and on the third whorl 2 mm. apart. 
Having no knowledge of the later stages of growth, of the aperture, 
or of the siphuncle it is impossible to give this form a definite generic 
position. The manner of coiling, however, strongly suggests the genus 
Discoceras to which the species is provisionally ascribed. 
In the preliminary report, I identified this specimen with Trocho- 
ceras insigne, Whiteaves, but a closer examination has induced me to 
alter my opinion. The original description of T. insigne (Ottawa Natu- 
ralist, Vol. XII, p. 124) carries the statement that the whorls are ‘‘closely 
contiguous’’, but the figure in Plate XLI, Vol. III of Palaeozoic Fossils, 
shows a shell with a gyroceran mode of coiling, not presented by our 
species. The costz in Whiteaves’ species are more widely spaced and 
turn apicad on the exterior margin, whereas in our species they are 
inflected slightly orad. 
The specimen bears some resemblance to Lituites bickmoreanus, 
Whitfield, but that species is more closely costated and the coste are 
directed apicad as they approach the venter. Further, the whorls 
expand much more rapidly in L. bickmoreanus. 
A stronger resemblance is presented by Goniatites? solitarius, Bar- 
rande, as figured on Plate 464, Systéme Silurien de la Bohéme; in fact 
the only difference seems to be a slightly more direct course in the 
costae of our species. Barrande’s specimen was obtained from Etage 
G, g1, at Hlubocep, which is too high for our specimen. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 325 S. Royal Ontario Museum of Palaeontology. 
