Leptoconus newtoni (Harris, 1897)

Protoconch small, composed of two and a half smooth turns, indistinctly striated with growth-lines anteriorly ; posterior portion slightly oblique with reference to the axis of the shell. Spire elevated, acute, convex, about one-sixth the total length of the shell ; spire-whorls seven in number, staged, excavated, spiral lineations bold and continuous, growth-lines prominent, sinuated. Keel sharp and plain, not being crenulated even in the brephic stage. Body-whorl elongate, ornamented throughout its length by distant spiral sulcations which are punctated where crossed by the lines of growth. Aperture long and narrow ; outer margin thin and arched; posterior sinus very deep ; anteriorly the aperture is somewhat dilated and the columella is slightly twisted ⁽¹⁾.

The elongation and narrowness of the body-whorl are distinctive features. Its nearest ally in the Australian Tertiaries is C. extenuatus (Tate, 1890) which, however, is broader, whilst its body-whorl is not so long, its periphery is not so sharply keeled, the earlier whorls are crenulated, and the ornamentation of the spire differs. C. newtoni closely resembles C. sieboldi (Reeve), living in the seas round the coasts of China and Japan, but in the modern form the whorls are not so much staged and the spiral lineations are not so well marked ; the principal point of difference, however, is the shape and shallowness of the posterior sinus.

Dimensions. — Length 62 mm.; breadth 26 mm.; length of aperture 52 mm.

Form, and Loc.— Miocene - Balcombiano: Muddy Creek, Victoria.

G. 4239. (NHMUK PI G 4239). One example. Presented by John Dennant, Esq.

G. 5494. (NHMUK PI G 5494).One example. Purchased. ⁽¹⁾

Characteristic gastropod of the Mediterranean-Iranian Province is, among many others, Conus (Leptoconus) diversiformis ⁽²⁾.

Widespread species which are recorded from both provinces and are therefore diagnostic (typical) of the entire Western Tethys Region are Conus diversiformis Deshayes, Conus carcarensis Sacco ⁽²⁾.

Bibliografia Consultata

• (1)  -  Catalogue_of_the_terziary_mollusca_australasia