Scenella tenuistpiata, sp. nov. (PI. LIX., Figs. 18 a, b).
Description. — Shell small, subconical; aperture ovate; apex
eccentric, obtuse, slightly incurved towards the longer extremity.
In side view boldly convex from apex to margin on shorter
side; on longer side concave under the apex, then becoming
convex and meeting apertural margin almost vertically. Surface
relieved with a few delicate subradial striae inclined towards the
longer side, otherwise smooth.
Dimensions. — Length, 2.75 mm.; width, 2.4 mm.; height, 1.6 mm.
Affinities. — Practically all the described species of the above
genus are from the Middle Cambrian; but there is an undescribed species from the Upper Cambrian (Potsdam Sandstone)
of Wisconsin mentioned by C. D. Walcott which may be at
least allied with, our form, as that author compares it with
(?) Scenella varians, a species from the Middle Cambrian of the
United States and Canada, resembling our fossil in some
particulars. The related genus Stenotheca occurs in the Cambrian of South Australia, and is distinguished from the above
genus by its stronger, rugose shell and curved beak. The latter
feature is not emphasised to any degree in our specimen, and
the smoother shell shows it to be distinct from Stenotheca in
that respect.
Horizon. — Upper Cambrian. Agnostus Zone. Dolodrook River.
