« EelmineJätka »
allied to M. multivolvis (Billings) which occurs in the Hudson River group at Anticosti; but in that species the whorls are still more flattened in the upper part.
Locality and formation.— At St. Ann's, on the Island of Montreal. Lot 12, con. 12 of the Township of Bagot, in the Calciferous sandrock at the Mingan Islands, in the White limestone. Collectors.—Sir W. E. Logan, J. Richardson. MURCHISONIA LINEARIS. (N. s.)
Fig. 8.-g. Description.-Very slender; elongated; apical angle about 10°; whorls twenty or more, convex. Length, two inches or more.
Of this species we have only impressions, but they are sufficient to shew that it differs widely from any other known in the Lower Silurian rocks of this country.
Locality and Formation.—Mingan Islands, White limestone. Collectors.—Sir W. E. Logan, J. Richardson.
MURCHISONIA ARENARIA. (N. s.)
Description. The cast of the interior of this species is conical; apical angle about 50°; whorls four or five, ventricose and obtusely angulated in the middle, where there is evidence of a spiral band. Above and below the band the body whorl is flattened or depressed convex, the upper whorls more evenly convex. Length, apparently, about three inches; width of body whorl, two inches.
The cast of this species somewhat resembles that of some of
the varieties of M. bellicincta. (Hall) but the spire is shorter and the whorls more angulated in the middle.
Locality and formation.- Lot No. 12, con. 12 Godmanchester, Calciferous sandrock.
Description.-Elongate; apical angle about 20°; whorls five or six ; depressed convex, or nearly flat in the middle ; length, four or five inches; width of body whorl about fifteen lines. Each whorl is about one-third shorter than the one preceding it.
This species, in its form and in the proportional length of the whorls, very closely resembles a species that occurs in the Trenton.
It appears to be more like a Loxonema than a Subulites. Locatity and formation.-Mingan Islands, Calciferous sandrock. Collectors.—Sir W. E. Logan, J. Richardson.
EUNEMA PRISCA. (N. s.)
Fig. 8.-1. Description. — Elongate; slender apical angle about 12°; whorls ten or twelve, each with two sharp keels in the middle, above and below which the surface descends with a gently concave slope to the suture. Length, from one inch and a half to three inches; width of body whorl in a specimen, nearly three inches long five lines ; width of spiral band, three-fourths of a line.
This species is only distinguishable from E. pagoda (Salter) by having no third keel near the suture.
Locality and formation.—Mingan Islands, Calciferous sandrock, and White limestone.
Collectors.Sir W. E. Logan, J. Richardson.
Genus ORTHOCERAS, (Breyn). The Orthoceratites of the Calciferous Sandrock and Chazy, have the same aspect as a group, and appear to be numerous, but are usually in a very bad state of preservation. Most of them
Fig. 11. Orthoceras Becki. b Orthoceras multicameratum ? Siphuncle.
Orthoceras Montrealensis. d Section shewing position of
siphuncle. e Longitudinal section. f-g Orthoceras Lamarcki. h Section. i-k Orthoceras sordidum.
are more or less curved and have large siphuncles, and several are remarkable for the close approximation of their septa.
ORTHOCERAS LAMARKI, (N. s.)
Fig. 11.-f, g, h. Description.—Annulated, tapering at the rate of about one line to the inch, section circular, septa gently convex, eight in one inch at a diameter of eight lines, more numerous towards the apex, siphuncle cylindrical a little excentric, its diameter full one third the diameter of the whole shell. The annulations are rather prominent rounded ridges with regularly concave spaces between, distant one line and a half from each other in a specimen eight lines in diameter.
The specimen figured is silicified, and it is impossible to say whether the surface is striated or not. Three specimens have been collected and all are a little curved.
The septa increase rapidly in number towards the smaller extremity of the shell and it would appear also that in some individuals the distance is variable. In one specimen where the diameter is five lines, there are five septa in half an inch, but in the next half inch there are eight.
The position of the siphuncle is also a little variable.
Resembles externally the large curved 0. subarcuatum, (Hall) of the Chazy limestone, but that species has more distant septa and a siphuncle composed of large oval bead-like segments.
Locality and formation.--Occurs at the Mingan Islands, and also on Lot 12, Con. 12, Township of Godmanchester, Calciferous Sandrock. Collectors.—Sir W. E. Logan, T. Richardson.
ORTHOCERAS BECKI, (N. s.)
Description.-Section circular, smooth, slightly curved, tapering at the rate of one line and one fourth to the inch ; septa rather convex, nine to the inch at a diameter of seven lines ; siphuncle cylindrical nearly marginal one third the whole diameter.
This species is allied to one that occurs in rocks of the same age in Scotland, figured in 3rd Edition of Siluria p. 217.
Locality and formation.-Mingan Islands, Calciferous Sandrock.
Collectors.-Sir W. E. Logan, J. Richardson.
ORTHOCERAS MONTRE ALENSIS, (N. s.)
Fig. 11.-c, d, e. Description.-Section circular, smooth, tapering at the rate of about one line to the inch: septa very convex, eighteen or twenty to the inch at a diameter of eight lines; siphuncle cylindrical marginal seven sixteenths the whole diameter of the shell surface unknown.
Locality and formation.—Near the village of St. Eustache, Calciferous Sandrock. Collectors.-J. Richardson, A. Murray.
ORTHOCERAS MULTICAMERATUM ? (Conrad.)
Several siphuncles have been collected in the Calciferous Sandrock at the Mingan Islands, which appear to be of this species. Specimens with the shell and septa preserved, occur at the same locality in Chazy limestone immediately overlying the rocks in which these siphuncles were collected.
ORTHOCERAS DEPARCUM, (N. s.)
Description.-Section circular smooth, tapering about half a line, and with thirty-two septa to the inch at a diameter of five lines. Siphuncle unknown.
This species tapers more gradually than 0. Montrealensis and has the septa more approximated. 0. primigenium, Conrad, is an allied species but with about forty septa to the inch according to the figure in the Palæontology of New York.
Locality and formation.—Mingan Islands, White Limestone. Collectors.—Sir W. E. Logan, J. Richardson.
ORTHOCERAS SORDIDUM, (N. s.)
Fig. 11.-i, k.
Description.-Cylindrical, apparently a little curved ; septa convex about twenty to the inch at a diameter of half an inch ; siphuncle marginal a little less than one third the diameter of the whole shell.
Resembles O. Montrealensis but is a more slender species and has the siphuncle smaller.