Box 14, Folder 3: Coal 1861

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ONCOCERAS ABRUPTUM, (n. s.)

Description. Shell small, gradually expanding from the outer chamber, and contracted again at the aperture. Very little curved, transversely round-oval, the greatest diameter being in a dorso-ventral direction, the two diameters being as seven and eight. Septa but little concave, not very distant, there being nine in the length of three-fourths of an inch from the outer chamber, counting on the side. Siphuncle dorsal.

Surface marked by longitudinal ridges, the remains of which are preserved on the cast.

This description is drawn from two fragments, one of which is nearly an inch and a half long, retaining eleven of the septa and a portion of the outer chamber; but the abrupt expansion of the shell, together with other characters, are sufficient to distinguish it from any described species. The transverse diameter of one fragment, where broken off, at the smaller end is seven-sixteenths of an inch, and at a distance of three-fourths of an inch it has increased to a diameter of seven-eights of an inch.

From the O. constrictum, of the Trenton limestone of New York, it differs in its more closely arranged septa, which are not arched forward on the dorsum as in that species, and also in its greater proportional transverse diameter.

Geological Formation and Locality. In the Trenton limestone group, at Platteville, and in the same position at Beloit, Wisconsin.

ONCOCERAS PLEBEIUM, (n. s.)

Description. Shell of medium size, rapidly expanding in the apical half, less rapidly in the middle, and again contracting near the aperture. Transverse section ovate, the diameter as seven to eight and a half, the longest diameter in the dorso-ventral direction, narrowest at the dorsum. Septa at medium distance, there being six in a space equal to their lateral diameter, little arched forward on the back, and but moderately concave. Siphuncle dorsal, of medium size, expanded in the chambers.

Surface unknown.

This species is subject to some variation in its curvature at different stages of growth, and also in the transverse diameter, some specimens being more compressed than others. It resembles O. constrictum, of the Trenton limestone of New York, in the unequal expansion, and in the flatness of the septa; but the expansion is not so abrupt, and the transverse section is proportionally much narrower.

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Geological Formation and Locality. In the Buff limestone of the Trenton limestone group, at Beloit.

Collectors. Prof. Nason, E. Hobart T. J. Hale.

ONCOCERAS PANDION, (n. s.) vol 1 [issue?] 41

Description Shell robust, strongly curved, very rapidly expanding to near the outer chamber, which gently decreases in size for nearly two-thirds of its length, and then becomes suddenly constricted to nearly half its former dimensions; broadly ovate or sub-circular, the diameter in the dorso-ventral direction. Septa moderately distant, strongly curved forwards on the dorsal side, the greatest concavity on the ventral side of the centre. Siphuncle large, dorsal.

Surface unknown.

This species most nearly resembles in form the O. constrictum of any species yet found in Wisconsin. The differences consisting in the greater proportional transverse diameter, the absence of a prominent or ventricose space on the ventral side at the point of greatest diameter, the greater concavity of the septa, and the more sudden contraction of the aperture.

Geological Formation and Locality. In "Buff limestone" of the Trenton limestone group, at Beloit, Wisconsin.

ONCOCERAS LYCUS, (n. s.)

Shell somewhat gently curving, gradually expanding from the middle to the outer chamber, which is marked by a broad, deep constriction just posterior to the aperture, the margin of which is expanded or sub-reflex. Transverse section very broadly ovate, the diameters as nine and ten, the longest being in the dorso-ventral direction; very obtusely snb-angular [sub-angular] on the back. Septa slightly concave, about a line apart, one or two of the outer ones a little more approximate. Siphuncle of medium size, expanded within the chambers, placed at about its own diameter within the dorsal margin. Length of fragments one to two inches. Entire length of larger specimens, three or four inches.

This species bears some resemblance to O. pandion in the form of the transverse section, and the constriction near the aperture, flut differs in the curvature of the shell, and in having less concave septa and position of the siphuncle.

Geological Formation and Locality. In the "Buff limestone" of the Trenton limestone group.

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ONCOCERAS ALCEUS, (n. s.)

Description. Shell robust, nearly straight or but slightly arcuate, rapidly expanding from the middle of the shell and and [and] swelling out more abruptly at the distance of an inch below the outer chamber, which gradually diminishes towards the aperture and constricted behind the margin. Transverse section elliptical, the longest diameter being as nine to twelve and a half. Septa about seven or eight in the space of an inch, very slightly concave. Siphuncle large, slightly inflated between the chambers, dorso-lateral or dorsal, being on the margin, half way between the line of the transverse and longitudinal diameters.

Some remains of strong lamellosc striæ of growth are preserved on the outer chamber. Length preserved, two and a half inches; the greatest diameter a little more than one and a quarter inches.

This species is remarkable for the straightness of the shell, and the elongate-elliptical form of the section. The position of the siphuncle may be considered as dorsal, it being upon the outside of the curve, the inner side of the curve and greatest attenuation of the septa being opposite. At first sight the position of the siphuncle appears to be due to distortion, but the relations of the parts have not suffered, and it does not seem possible that it could have been moved by pressure without distorting the form and proportions of the parts.

Geological Formation and Locality. In the "Buff limestone" of the Trenton limestone group, at Beloit, Wisconsin.

ORTHOCERAS GREGARIUM, (n. s.)

Description. Shell of medium size, gradually expanding from the apex; transverse section circular. Septa deeply concave, not very distant, varying from six to nine in the space of an inch, according to age. Siphuncle central in young specimens, often becoming sub-central or quite excentric [eccentric] in old individuals.

Surface smooth except fine concentric lines of growth.

This species somewhat resembles some specimens of O. proteiforme of the Trenton limestone of New York; but it differs in the uniformly smaller size, greater concavity of septa, and more central siphuncle; while in that species the siphuncle is sub-marginal.

Geological Formation and Locality. Abundant in the lower part of the shales above the Galena limestone; at Makoqueta

47 creek, in Iowa; at Scales Mound in Illinois; and, more rarely, in the beds of which this group have been penetrated in the mining district of Wisconsin.

ORTHOCERAS PLANOCONVEXUM, (n. s.)

Description. Shell of medium size, gradually expanding from the apex towards the outer chamber, plano-convex; transverse section semi-circular or sub-triangular, the diameters as five to nine. The convex side is a little depressed on each side of the middle, the opposite side nearly flat, the edges abruptly rounded. Septa moderately concave, arching upwards on the sides, somewhat closely arranged, about five in half an inch. Siphuncle small, central. A specimen of the outer chamber, apparently of this species, is a little more than two and a half inches in length, and one inch and an eighth in width, the short diameter being half an inch; the septa are about one-tenth of an inch distant.

Surface unknown.

Geological Formation and Locality. In the Buff limestone of the Trenton limestone group, at Mineral Point and Beloit, Wisconsin.

GONIOCERAS OCCIDENTALE, (n. s.)

Description.

Shell elongate, very compressed, extremely expanded laterally, the upper part with curved outline, beyond the middle the edges are more nearly parallel; the length (when entire,) having been a little less than twice the greatest diameter. Upper and lower surfaces convex, the one twice as convex as the other; the two diameters as one to seven; lateral expansions very thin. Septa deeply concave, numerous, closely arranged, twelve to the inch in the central lobe; arching forwards on the sides with a sharp retral curve a little within the margin, and running backwards in a narrow extension to the edge at a point opposite or below their junction with the siphuncle in the central lobe. Siphuncle oblate, of medium size where passing through the septa, expanding in the chambers to more than one half the smaller diameter of the shell, somewhat bilobate from a constriction above and below.

Surface apparently smooth, or with only concentric lines of growth.

This species differs from G. anceps, of the New York rocks, in the less rapid and irregular lateral expansion from the apex, in being thinner in proportion to the breadth, in the more reg

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larly convex sides, and in the form of the septa, which are more deeply concave in the middle lobe; this part being narrower in proportion to the entire breadth. In the lateral expansions or outer lobes the septa are recurved towards the apex, and gradually approach each other towards the margin; while in the G. anceps they make a gentle backward curve and terminate on the edge at nearly their full width.

Geological Formation and Locality. In limestone of the age of the Trenton group, at Platteville, Wisconsin.

GENUS THECA, Sow.

THECA PRIMORDIALIS, (n. s.) see Vol 1 [issue?] 21

Description. Shell elongate, gradually tapering to the somewhat obtusely pointed apex. Transverse section sub-triangular or plano-convex, the diameters about as two to one; length of shell about three and a half times as great as the width of the aperture; one side very slightly convex or nearly flat, the opposite side often regularly rounded, sometimes a little angular along the centre. Aperture transverse, the margin on the flat side extended and forming a semi-circular lip; that of the convex side transverse to the axis of the shell with sometimes a slight emargination near the middle.

Surface marked by fine lines of growth parallel to the margin of the aperture, and also on the flat side by numerous strong undulations following the lines of growth. The shell, where preserved, is apparently phosphoric, having the same texture and appearance as the Lingulæ, with which it is associated; but it is more readily decomposed. It sometimes attains a length of one inch and a quarter.

Articulata

Geological Formation and Locality. Potsdam sandstone, Trempealeau, Wisconsin, and Chippewa River.

GENUS SERPULITES, MCLEAY.

SERPULITES MURCHISONIA, (n. s.) Vol 1 [issue?] 21

Description. Body elongate, extremely compressed, very gradually tapering to the acutely pointed apex, gently curved throughout its entire length. Both sides (as they are embedded in the sandstone,) very depressed convex, with the aperture prolonged on the inner side of the curve, [.]

Surface of both sides marked by fine transverse lines of growth, and by numerous strong somewhat equidistant undulations, parallel to the margin of the aperture. Length of a