Genus Pukeuria nov.
Type: Pukeuria anaglypta n.sp.
The depressed, tilted embryo with blunt summit points to affinity with the Pyrgulinids. The important post-nuclear characters are the presence of axial ribs extending from summits of whorls to periphery, below which they begin to evanesce, ultimately dying out well down on the base; between sutures the intercostal spaces (on later adult-whorls only) carry weak spiral threads, but below the periphery these become much more elevated and regular, and surmount the prolongations of the axial ribs; the whorls are short between sutures; the aperture is broadly subovate to subquadrate and the columella bears near its insertion a low fold, which strengthens internally; there is a cord on the sub-angled periphery.
Several genera call for consideration in allotting this shell to its group. The presence of spiral threads on the base precludes Parthenina Bucquoy, Bautzenberg and Dollfus; Besla Dall and Bartsch has a spirally striated base, but it is a different style of shell and the spirals between sutures are confined to several distinct threads at and just above the periphery; Egilina Dall and Bartsch is of somewhat similar build, but lacks spirals between sutures and has very strong basal cords. It is obvious that the characters of the New Zealand fossil do not permit natural reference to any of these groups, and the new name Pukeuria is accordingly provided for it.
Pukeuria anaglypta n.sp. (Fig. 25.)
Shell moderately large, stout, conic, not attenuate, height of spire three times that of aperture, outlines straight. Post-nuclear whorls 6½ in number, lightly and evenly convex; suture distinct though not deeply incised. Protoconch heterostrophic, small, considerably depressed and tilted, so that summit of shell appears blunt; no nucleus visible. Axial ribs (about 20 on penultimate whorl) straight, usually vertical, but sometimes a little oblique, extending from summit of whorls to peripheral cord as stout costae, thereafter on base becoming evanescent towards umbilical region; intercostal spaces excavated, greater in width than ribs; weak spiral threads are present in interstices of later whorls, but on the base they become distinctly elevated, more regular, and surmount the dying axial corrugations. Body-whorl in height less than one-half that of shell, lightly convex to flattish above, periphery angulated (sharply in juvenile shells) and carrying a cord at which the sudden change in strength of axial ribs takes place; base lightly and regularly convex; aperture broadly subovate to subquadrate, the posterior angle wide; columella broad, vertical, lightly arcuate, a small but distinct fold high up; inner lip callused within aperture; basal lip broadly rounded; outer lip straight.
Height, 5·5 mm.; width, 2·6 mm. (holotype).
Localities: Pukeuri, near Oamaru (many specimens), type; Rifle Butts (a single perfect specimen); Awamoa Creek (a juvenile). These are Awamoan horizons near Oamaru. Also Mahoenui beds, Awakino Gorge (Hutchinsonian).
Type in Auckland Museum (ex writer's collection).