e::?docekatid^. 
163 
1863. Piloceras Canadense, Billings, Geol. of Canada, Appendix, p. 951. 
1864. Piloceras Canadense, Murray, Geol. Sury. of Newfoundland, 
Eeport for 1864, p. 23. 
1865. Piloceras Canadense, Billings, Pal. Foss. yol. i. p. 256. 
? 1866. Cyrtoceras. Espece indeterminee, Barrande, Sjst. Sil. de la 
Bohenie, yol. ii. pi. ccxx. IF. 6-8. 
S]p. Char. “ The form, as nearly as it can be determined, is that 
of a short, thick, ciiryed Orthoceratite. The length of the largest 
specimen appears to haye been about ten inches, and the diameter at 
the aperture four or fiye inches. The transyerse section is oyal, the 
narrowest side being that of the concaye curyature. The siphuncle 
of one specimen is, at two inches and three fourths from the apex, 
seyenteen lines in diameter in the clorso-yentral direction, and four- 
teen lines in the transyerse direction. On the surface of this speci- 
men there are, on an ayerage, six septal rings in the length of one 
inch. Judging from the appearance of another specimen, the posi- 
tion of this siphuncle would be close to the yentral side of the shell. 
Another sij^huncle about the same size shows scyen septal rings to 
the inch. In a third, consisting of a portion of the larger extremity 
of an indiyidual which, when perfect, must haye been at least nine 
inches in length, there are six septa partly preseryed, apparently 
those next the aperture. They are distant from each other about 
liye lines, the whole being comprised within a length of thirty lines. 
The shell where these septa are situated is at least four inches in 
diameter in the transyerse direction, and the siphuncle about two 
inches. The edges of the septa, in crossing the yentral or concaye 
side, make at the surface a short curve towards the apex ; but on the 
siphuncle the septal ridges cross from the dorsal to the yentral side 
obliquely, so that on the yentral side they are some^yhat nearer the 
aperture than they are on the dorsal side. ... On comparison with 
Salter’s P. invaginatum, it will be seen that the septal rings do not 
cross the siphuncle in the same direction as they do in ours, and 
further, that that species is more broadly curyed.” (Billings.) 
Horizon. Calciferous Formation ( = Tremadoc). 
Locality. Mingan Islands, Gulf of St. Lawrence. 
Bepresented by two siphuncles, one of them presented by the late 
E. BiUings, Esq., F.G.S., and the other transferred from the Museum 
of Practical Geology. 
