Valvobifarina mackinnonii (Millett, 1900a)

Figure 10.10

1900a Bifarina mackinnonii Millet, p. 281, pl. 2, fig. 15a-b.

1951 Valvobifarina mackinnoni (Millett); Hofker, p. 40, figs. 16-17.

1994 Valvobifarina mackinnoni (Millett); Loeblich and Tappan, pl. 254, figs. 9-12.

Description. Test long, wall calcareous, surface ornamented with slightly produced circular pores and acicular spines in the final chambers; chambers initially triserially arranged, later biserially and uniserially arranged; periphery angular, sutures distinct; oblique in later chambers; aperture a broad, horizontal slit-like opening, bordered by a thick lip.