28 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
The interior of the siphuncle shows about 20 longitudinal plates, 
radiating from a central endosiphuncle, which, however, is inferred but 
not observed. This internal support for radiating tubuli is very different 
from that of other species, in which it seems to take the form of annular 
membranous or calcareous expansions. 
The height of the segments and the nature of ie outline are very 
like those of Huronia turbinata, Stokes (Trans. Geol. Soc., Ser. II, 
Vol. I, Pt. II, explanation of Plate XXVIII, Fig. 3: and Page 203, 
Species III of Bigsby), but our specimen is relatively much wider. 
An example in the Royal Ontario Museum referred to H. turbinata 
measures as follows: Height of segment I9 mm., greatest width 30 mm.; 
least width 18 mm. It is to be concluded that our specimen is of the 
same general type as H. turbinata but that it is not co-specific. The 
general assemblage of fossils at the Lower rapids of the Shamattawa 
river indicates Ordovician rocks: if the present specimen was really 
obtained in situ, the range of the genus Huronia is considerably ex- 
tended, for it has hitherto been reported only from the Niagara group 
of North America. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician? 
No. 312 S. Royal Ontario Museum of Palaeontology. 
CYCLOCERAS (?), sp. indet. 
Plate II, Figure 7. 
One fragment of a cast: 25 mm. long, 15 mm. in diameter at anterior 
end and 14 mm. at posterior end. Surface marked by oblique and sharp 
crested annulations about 3 mm. apart. Straight or slightly coiled. 
A vertical section shows no internal structures. 
As the test is not preserved, even the generic position of this frag- 
ment is doubtful, but it would fall under Cycloceras, Spyroceras or other 
related annulated genera. 
The specimen bears some resemblance to Spyroceras meridionale, 
Whiteaves,! from the Silurian of Stonewall, Manitoba. Our form differs 
in the less rapid taper and the more uniform distance apart of the 
annulations. 
The specimen bears considerable resemblance to Cyrtoceras nitidium, 
Barrande, from Etage E of Bohemia,’ but perhaps the most striking 
comparison, may be made with Orthoceras anellum, Conrad,’ from the 
1 Geol. Sur. Can., Palaeoz. Foss, Vol. III, p. 281, pl. 30, fig. 9. 
2 Systéme Silurien de la Bohéme, pl. 198, figs. 21-35. 
8 Proc. Acad. Nat. Sci., Phil., 1843, p. 334; Pal. N.Y., Vol. 1, p. 202, pl. XLII, fig. 6; 
Geol. Rept. Wisconsin, Vol. I, p. 442, 1862; Ibid., Vol. IV, p. 226, pl. VII, fig. 13, 1882. 
