(

ciated with the genera Ophileta and Maclurea in this country. Their Maclurea Peachii has a long spiral operculum, very unlike anything then known on this side of the Atlantic, and it was not suspected that the.genus Piloceras would ever be found here at all. But we have now not only a species of Piloceras (from the Calciferous Sandrock) but also Maclurea Atlantica (from the Chazy) which latter species has an operculum almost identical with that of O. Peachii. When it is considered that evidence of this kind as it accumulates increases in its demonstrative power in a much higher ratio than do the mere number of the species (or the facts which constitute the data) the correctness of the view that the Scottish and Canadian rocks above referred to are of the same age, cannot fail to be perceived.

Fig. 16.-Side view of the solid portion of the siphuncle shewing distance of the septa.

Description. Of this species we have, besides several detached siphuncles, two fragments, each exhibiting some of the septa. The form, as nearly as it can be determined is that of a short thick curved Orthoceratite. The length of the largest specimen appears to have been about ten inches, and the diameter at the aperture four or five inches. The transverse section is oval, the narrowest side being that of the concave curvature. The siphuncle of one specimen is, at two inches and three-fourths from the apex, seventeen lines in diameter in the dorso-ventral direction, and fourteen lines in the transverse direction. On the surface of this specimen there are, on an average, six septal rings in the length of one inch. Judging from the appearance of another spe

cimen, the position of this siphuncle would be close to the ventral side of the shell. Another siphuncle about the same size shows seven septal rings to the inch. In a third, consisting of a portion of the larger extremity of an individual which, when perfect, must have been at least nine inches in length, there are six septa partly preserved apparently those next the aperture. They are distant from each other about five 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 transverse direction, and the siphuncle about two inches. The edges of the septa, in crossing the ventral or concave side, make at the surface a short curve towards the apex, but on the siphuncle the septal ridges cross from the dorsal to the ventral side obliquely, so that on the ventral side they are somewhat nearer the aperture than they are on the dorsal side.

The above are all the details of this species of any importance. furnished by our specimens. 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 curved.

Locality and Formation.-Mingan Islands, Calciferous Sandrock.

Collectors.-Sir W. E. Logan. J. Richardson.

Fig. 17.-Cyrtoceras exiguum. Outline of a specimen.

The dotted

lines represents the supposed outline of the smaller extremity.

18. A specimen shewing the depth of the chamber of habitation and five of the air chambers.

Description.-Small, slender, slightly curved; section circular. One of the specimens examined is three lines in diameter at the aperture and apparently a little less at one line and a half above. The shell then expands to a diameter of four lines at the distance of five lines from the aperture. It then tapers to two lines at a

length of thirteen lines; thence to the apex unknown, but probably terminated at a length of eighteen or twenty lines. One side of the fragment is nearly straight. No septa or siphuncle observed in this specimen, but the form alone is sufficient to distinguish the species from any other known in the Lower Silurian of this country. Associated with the one above described was found another fragment ten lines and a half in length. Width at aperture three lines; diameter at five lines from aperture four lines; length of chamber of habitation five lines and a half. Next to the chamber of habitation five of the septa are preserved and they occupy a length of exactly five lines; the siphuncle not visible.

Locality and Formation.-Near L'Orignal, Trenton limestone. Collector.-R. Bell.

Fig. 19.-Phragmoceras præmaturum. Aperture of a specimen. 20. Side view of a different individual.

Description.-Ventral aspect with the convex curvature; dorsal aspect concave; section oval narrowly rounded on the ventral aspect; depressed convex on the sides and broadly rounded on the dorsum. In the first inch and a half of the length the ventral side forms a curve of which the radius is about one inch; the re mainder of the curve to the apex unknown. The aperture is broadly rounded on the dorsal side; at about one third the dorso-ventral diameter it begins to contract; at two thirds its diameter its transverse width is about half its greatest width; thence to the ventral margin the sides are sub-parallel, gradually approaching each other; the ventral margin narrowly rounded. On a side view the dorsal two thirds of the aperture is obliquely truncated

towards the apex while the ventral third slopes so as to form an obtusely rounded right angle with the dorsal two thirds. The aperture is thus obscurely trilobed, the ventral lobe being the smallest and forming a deep narrow sinus in the ventral margin. At the aperture the greatest transverse width is six lines in the specimen on which the species is founded; the dorso-ventral diameter eight lines. At seven lines (from the most prominent point of the aperture on the side) we find the greatest transverse diameter which is here seven lines and a half and the dorso-ventral diameter nine lines. At the length of one inch and a fourth the dorso-ventral diameter is reduced to between five and six lines. The remainder of the specimen is not preserved. The depth of the chamber of habitation is ten lines. The first five septa occupy six lines of the ventral margin, but at the middle of the lateral aspect four lines and a half. Siphuncle about one line in diame ter and apparently in contact with the shell along the median line of the ventral side. The surface of the shell is covered with fine striæ or rather small smooth continuous wrinkles which encircle the tube following the curves of the aperture. These wrinkles vary in size, but in general there are five or six in the width of one line.

The majority of the species of this genus have the siphuncle on the inside or close to the shell on the side of the concave curvature. M. Barrande, however, has one species P. perversum in which it lies close to the outer curve. The aperture is not so strongly trilobed as it is in Upper Silurian and Devonian species. I believe this is the only Phragmoceras known in the Lower Silurian Rocks.

Locality and Formation.-The specimen figured was found on Le Cloché Island, Lake Huron, in the Black River Limestone. Two other fragments have been collected, one at La Petite Chaudière Rapids and the other at Pauquettes Rapids, Ottawa River, in the same formation

Collectors,-Sir W. E. Logan, R. Bell, E. Billings.

Description.-Small, section sub-oval; broadly rounded on the dorsal and very gently convex on the ventral aspect; sides ∙nar

• See translation of Barrande's note on the Silurian Cephalopoda of Bohemia, Jour. Geo. Soc. Vol. X. Translations p. 21.

rowly rounded. Siphuncle very small, close to the ventral margin slightly dilated between the septa; of these latter there are six in three lines where the transverse diameter of the shell is five lines.

The dimensions of the best preserved specimen that I have seen are as follows. Length of specimen twenty-two lines; transverse diameter of aperture seven lines; dorso-ventral diameter of aperture five lines; depth of chamber of habitation, twelve lines; transverse diameter at smaller extremity of specimen four lines nearly; dorso-ventral diameter three lines nearly. In the length of twenty-two lines measuring from the aperture this specimen tapers three lines in the tranverse diameter and one line in the dorso-ventral diameters. The width of the siphuncle between the septa is about three-fourths of a line; its passage through the septa is a small circular aperture scarcely one third of a line in diameter. At the smaller end of this specimen the greatest transverse width is about one fourth the dorso-ventral diameter from the ventral margin. The aperture is more nearly a regular oval. The siphuncle is in the middle of the ventral aspect. The shell is gently curved towards the dorsal side.

This species is related to both O. xiphias and O. hastatum, (Report for 1856, p. 318 and 333) but the proportions are very different. In O. xiphias the two diameters of the aperture are to each other as 7 to 3, but in O. tener they are as 7 to 5. 0. hastatum tapers at the rate of about 4 lines to the inch, while in O. tener the rate is scarcely two lines.

Locality and Formation.-Black River limestone. Pauquettes Rapids.

Collectors.-Sir W. E. Logan, E. Billings.

Description. The specimen on which this species is founded. is two inches and five lines in length; nine lines in diameter at the larger and seven lines at the smaller extremity; section circular; septa distant three lines at the large end and two lines and a-half at the small end. The siphuncle is moniliform its centre distant two lines from the margin where the diameter is seven lines; the expansions are sub-globular and about two lines or a little more in their greatest diameter. The septa have a convexity equal to about half their distance from each other and they cross the tube obliquely so that their edges at the surface on the