Genus Ceratobulimina Toula, 1920.
Genotype (monotypic): Rotalina contraria Reuss; Zeitschr. deutsch geol. Ges., 1851, vol. 3, p. 76, pl. 5, fig. 37 (Oligocene, Germany).
Galloway's Manual gives the date of Toula's work as 1915; I am unable to check it.
There seem to be more than one group included in the species discussed by Cushman and Harris (1927, p. 171–176, pl. 29). The forms represented by C. hauerii (d'Orbigny) with their plate-like extension completely covering the aperture are in New Zealand quite distinct from those of the C. pacifica Cushman and Harris type, in which the aperture is always perfectly open and is a much narrower slit; this aperture is not so well seen in the figure given by them as it is in Brady's (Chall. Zool., vol. 9, p. 54, fig. 18). Forms resembling the variety australis of C. hauerii are not uncommon in New Zealand and perfect examples always show an unslit terminal face, the plate leaving merely a Discorbis-like aperture, but being noticeably thinner over a relatively wide medial tongue-like area, somewhat as in Cancris. No narrow slit is observable in these specimens. Only when broken do they show the tongue-like area open and inclined to one side of the terminal face. Individuals of the pacifica group never have a projecting plate even when fully adult. Shells at all stages show a deep, narrow slit extending straight into the terminal face for some distance. In both groups broken shells show that earlier chambers have the opening filled in from the umbilicus to leave only a sub-oval chink at the extremity of the tongue. This is less than halfway down the face in the hauerii type; more than halfway in pacifica. The faint groove on the terminal face seen in illustrations of the hauerii group apparently merely marks one side of the wide tongue, and is not the complete homologue of the pacifica furrow. The length of this feature seems to vary; in New Zealand, specimens of the former group always have it considerably shorter than those of the latter, but the Australian hauerii var. australis has it fairly long in the illustrations.
The presence at all, however, of a completely covering plate in some species, and its total absence in others, whose adults develop instead a normal deep and long cleft, is an apertural feature worthy of subgeneric status. The figures of Reuss's contraria show a long deep groove, without covering plate, so that the new group must be for the other type.
Ceratobulimina (s.str.) kellumi n.sp. (Plate 13, fig. 60.)
Shell at least one and a half times as long as broad, compact, very inflated, elongate-globular, with no pronounced angles; six chambers in last whorl. Sutures distinct, practically flush with surface, usually markedly limbate, depressed into short furrows near umbilicus, which is practically closed. Aperture a very deep, narrow, entirely open furrow, extending from umbilical area two-thirds of distance into terminal face, slightly sigmoid, about one-fifth width of face. Dorsal surface tightly coiled, smoothly and evenly rounded; earlier chambers forming an almost flat top, spiral suture distinct but not sunken.
Length, 0.65 mm.; width, 0.45 mm.
Holotype from locality 4270, Tangihanga, Waikohu Surv. District, Poverty Bay. Horizon, Ihungian, i.e. Hutchinsonian, close to Awamoan.
Quite a number of perfect specimens in all stages occurred here and no trace of a covering plate is ever developed. Also common at 3029, Ihungian sandstone, Whangara beach, and at G.S. 1342, Waikura Stream (Tutamoe). In the definite Tutamoe, i.e. Awamoan, it occurs at G.S. 1296, Muddy Creek, is common at 1186 (Avondale Station) and 1195 (Te Aroha Stream), and continues into the Taranakian (3137, Kaiti Beach, and 4256, Ngatapa, both Poha formation). All these localities are in Poverty Bay, and so far the species has not often been seen elsewhere, nor in company with the previous one; that it has a longer range is evident from the occurrence of a few typical examples in the Waitakian of McClay's Farm, Otama Valley, Southland (G.S. 1909) and one in equivalent beds at Waikaia (5387).
It is named after Dr. L. B. Kellum, Chief Geologist of the New Zealand Petroleum Company, at present working in this area.
Ceratobulimina (s.str.) lornensis n.sp. (Plate 13, fig. 61.)
Shell sub-circular, almost as broad as long; last chamber somewhat projecting, considerably inflated, not compressed. Six chambers in last whorl, progressively more separated as growth proceeds so that sutures become deeper and periphery more lobulate anteriorly; last chamber irregularly bulbous, with a rounded or slightly flattened terminal face into which projects for one third to half its length a narrow, not very deep, apertural furrow. Umbilicus widely open, about a quarter of width of shell, overlapped for half its width by free margin of last chamber before it joins previous whorl. Dorsal side with the radial sutures of last three chambers distinct, all others obscure. No ornament, surface smooth.
Length, 0.75 mm.; width, 0.65 mm.
Holotype from Lorne (5064), type of Waiarekan. Horizon basal Kaiatan, i.e. Lowest Oligocene. Not known from any other locality.
In its flattish sub-circular shell this differs conspicuously from the Miocene kellumi, and can be compared with the American Lower Eocene C. perplexa (Plummer). The figures of this species given by Cushman and Harris (l.c., page 173, pl. 29, figs. 2 a-c), show that it is considerably more compressed vertically, giving it an acutely instead of bluntly rounded periphery. It has a similar short apertural cleft and open umbilicus less encroached on, however, by final chamber, and has conspicuous sutural ornamentation on the dorsal side. A species with even closer affinity is the recently described C. westraliensis Parr (1938, p. 83, pl. 2, figs. 12 a-c). This is a common species in the Upper Eocene of Western Australia and was also compared with perplexa; the figures show it to be of similar
inflation but with a still more extensive umbilicus and aperture notch and with chambers more numerous and more distinctly marked off. It is interesting that these three similar forms should all be from the Lower Tertiary.