Clathrospira subconica

• A medium sized, broadly turreted species
• Whorl profile strongly subangular at the periphery
• Has a deep V-shaped sinus in the outer lip culminating at the subangular periphery in a short slit or notch
• Has a higher arcing spire
• Wider, more strongly defined selenizone that is visible in previous whorls

Fossils of Ohio (1996):

• Clathrospira subconica (Hall) is a medium –sized, broadly turreted species.

Rohr (1996):

• Clathrospira subconica (Hall), 1847, the most widespread North American species of the genus has a higher spire and a more strongly defined, wider selenizone which is visible in previous whorls.

Knight (1941):

• Turbiniform, narrowly phaneromphalous gastropod of moderate size with a deep V-shaped sinus in the outer lip culminating at the subangular periphery in a short slit or notch that gives rise to a gently concave selenizone; whorl profile strongly subangular at the periphery, above the periphery gently convex on the upper and gently concave on the lower part, periphery truncated by the vertical selenizone; sutures shallow, the lower line of suture falling just below the selenizone; nucleus unknown; base gently arched, narrowly phaneromphalous; columnar lip seemingly thin and reflexed about the umbilicus; parietal inductura thin; outer lip with a deep V-shaped sinus culminating at the periphery in a short slit which gives rise to the selenizone, the margin of the lip passing from upper suture to the selenizone with strong backward obliquity and gently forward convexity, the obliquity increasing as the selenizone is approached, below the periphery strongly oblique forward for a short distance the gradually turning with marked forward convexity until a radial direction is assumed on the inner half of the base; selenizone gently concave between low bordering carinae, lunulae simple, some at rather regular intervals stronger than the others; ornamentation transverse lines of growth and very fine revolving lirae; shell thin, its structure unknown.

Foerste (1924):

• Shell with relatively straight profiles along its upper face, from its apex to the angular peripheral outline. Slit-band vertical, occupying the outer edge of periphery. Lower margin of the slit-band in contact with top of the next following whorl. Lower surface of the body whorl evenly convex.
• Locality and Horizon. Originally described from near the base of the Trenton in New York. Apparently ranging from the Black River and Trenton to the Richmond, from New York and Canada to Ohio, Tennessee, Iowa, and Minnesota. Two specimens, No. 8458 a and b, were found in the Nicolet River section, the first in the Waynesville. It is 30 mm. in height, apical angle 75 degrees. The second specimen was found 77 feet below the horizon at which Rhynchotrema perlamellosa is associated with the lowest specimens of Strophomena planumbona. A specimen, No. 8459, 20 mm. high, apical angle 72 degrees, was found at Clay cliffs, in the Meaford. Another specimen, No. 8486, was found at the same horizon 7 miles north of Meaford, along the hill front west of the road to Cape Rich. It is known also from the Waynesville member near Vars. At Weston, Ontario, it occurs in the Pholadomorpha zone.

Ulrich & Scofield (1897):

• Shell with a short conical spire, consisting, when fully grown, of six and a half or seven volutions, of which the two at the apex are usually broken away; greatest width and height nearly equal, varying generally between 25 and 30 mm., but attaining occasionally a width of over 40 mm., apical angle 70 to 80 degrees, but in four specimens out of every five the variation is only about one degree either way from 74 degrees. Volutions flattened above in the direction of the slope of the spire, the inner portion of slope gently convex, the outer half correspondingly, or more strongly concave; convex portion of slope just touching or failing to reach a line drawn from periphery to periphery of succeeding whorls; under side of whorls rounded, occasionally very slightly concave near the periphery, this condition appearing, however, only in specimens in which the band is unusually prominent, umbilical depression small, terminating generally in a minute axial perforation. Band prominent, sharply defined, rather wide, concave, nearly vertical, situated on the periphery of the last volution, and lying immediately above the suture line on the upper whorls. Aperture subquadrate, outer lip broadly notched; columellar lip not very strong, thin, folding about the small umbilical perforation. Surface sculpture beautifully cancellated, consisting of two sets of fine, subequal, thread-like lines, one revolving, the other running parallel with the margin of the aperture. The transverse lines, of which three to five occur in the space of 1 mm., are recurved as usual on the upper side and quite as much on the lower side. At intervals, sometimes quite regular, many specimens exhibit more or less distinct undulations of growth, in some examples little more than a millimeter apart, in others two, three, or four millimeters. Considerable variety as regards strength and arrangement of the lines forming the surface sculpture may be observed in specimens from different localities. As a rule the revolving lines are strongest on the basal portions of the shell, and in some of the specimens from the “Glade limestone” of Tennessee they appear to be wanting entirely on the upper side. In the latter cases the transverse lines are stronger than usual. In all the specimens from the Stones River group of Illinois, Wisconsin and Minnesota that retain the markings, the two sets of lines are almost equally developed, and on the whole finer than on the Tennessee shells. The lunulae of the band are distinct, strongly curved, and crossed by a varying number of delicate revolving lines. Suture linear and inconspicuous except between the last two whorls of old shells. The last volution usually descends more rapidly than the preceding whorls.

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