Conus ptychodermis

Conus ptychodermis (Tate, 1890)

Descrizione:

Shell narrow, conoidal, a little more than twice as long as wide ; spire very low, ending in a small obtuse pullus of two smooth whorls. Spire consisting of four and a-half narrow flat whorls separated by a narrow channelled suture; ornamented spirally by a medial, more or less prominent, thread, with or without a few threadets, crossed by arched prominent growth-ridges and by coincident stride.

Body-whorl obtusely angled at the periphery, regularly tapering to the front; ornamented by inconspicuous spiral threads, which are wrinkled by the intercrossing of growth-folds, between which the surface is slightly contused.

Dimensions. — Length, 30; greatest width, 13; height of aperture, 28.

Locality, — Eocene beds at Muddy Creek.

This species may be readily distinguished from all other Australian Tertiary Conus, by the peculiar, rugged aspect of the body-whorl caused by the inter-crossing of growth folds and the irregular character of the distant spiral lineations and ridges. The spire is much depressed, with canaliculated sutures; the periphery of the body-whorl is sharply keeled ; the anterior portion of the columella is twisted and prominently lineated. The protoconch is not well preserved in the Museum specimen, but it evidently had the general features of that of C. pullulescens, though more depressed.

Dimensions. — Length 20 mm. ; breadth 9 mm. ; length of aperture 17mm.

Form, and Loc. — Miocene : Muddy Creek, Victoria. G. 5489. One specimen.