Description of lectotype: The fairly large test consists of slightly more than two whorls of strongly inflated chambers arranged 3 to a whorl in a moderately high trochospire. The equatorial profile is subovate, but the equatorial periphery is strong lobulate. The dorsal surface is distinctly convex and the earlier whorls are clearly visible. The chambers are subglobular to sub-ovoid and are broadly reniform in dorsal aspect, well separated one from the other and are but little embracing. The sutures are distinctly and broadly depressed both dorsally and ventrally; they are strongly curved dorsally, but also radial ventrally. The apertures are multiple. primary aperture is interiomarginal umbilical, a moderately high, semicircular arch bordered by a distinct, uniformly narrow, I rim; the primary aperture is placed and shaped symmetrically with respect to the intercameral suture between the penultimate and antepenultimate chambers. The supplementary apertures are dorsal in position and are situated at the basal suture of each chamber at its junction with the adjacent intercameral suture of the preceding whorl. One or two such supplementary apertures are present in each chamber of the last whorl. The supplementary apertures are high, semicircular arches, with very thin rims. The umbilicus is small, almost closed and very shallow. The waH is calcareous, apparently radial in structure, uniformly and fairly finely perforate and moderately thin. The surface of the test is slightly rough, but little trace of any original hispidity exists in the lectotype. .The earlier part of the test is red coloured, not with the red tint of ferric compounds, but with a deeper and morecrimson hue, probably of an organic origin. [Banner & Blow 1960]

Maximum diameter of lectotype: 0.56 mm. [Banner & Blow 1960]

Taxonomic remarks: Very many references to this species have been made in the literature and it is impossible for us to attempt a complete list of synonymous references here. Those given above merely trace a historical outline of the usage of Brady's name "sacculifera."" Further points concerning this are discussed below the Remarks.

Brady first validly described this species in 1877 when he discussed material obtained from a fragment of ""?Chalk"" (a soft white calcareous rock) which had been found on a beach by Liversidge in New Ireland (Territory of New Guinea) after an earthquake. He believed that the rock was ""a compact fragment from a recent sea bottom,"" but it is more likely to have been of Upper Miocene or Pliocene age. It is from this ""material that Brady's original syntypic series of specirrit;ns was obtained. They are extant in the collections of the British Museum (Natural History) and slide registered as number P. 43317 contains them. It is marked ""White Chalk; New Britain (Liversidge)"" in Brady's handwriting and ""Post Tertiary, New Ireland, Geol. Mag., Dec. 1877, p. 535"" in another handwriting. New Britain and New Ireland are in the same group of Islands (Bismarck Archipelago) and seem to have been confused by Brady in his notes though not in his publications.

The lectotype, here designated, of Globigerina sacculifera Brady 1877 has been isolated from this slide and is now registered in the collections of the British Museum (Natural History) as registered number P. 44033.

Brady first illustrated this species in 1884 when he described recent material collected by the ""Challenger"" Expedition from the North Pacific, Atlantic Ocean and the Caribbean area. The specimen figured by him (op. cit.) on pl. 80, figure 11, is ideotypic (not syntypic) and its ventral view is illustrated for the first time (pl. 4, fig. 2). This specimen is now registered in the British Museum (Natural History) as number 1959.4.13.8. It was obtained from slide no. 85.10.5. 482., which contained 49 specimens from Challenger Station 224, 1850 fathoms, North Pacific. [Banner & Blow 1960]

Brady's syntypic series of specimens from a probable Uppermost Miocene horizon all show the same characters relating to the final chamber as here illustrated for the lectotype. The constancy of the ""saclike"" nature of the final chamber for any particular stratigraphic horizon is quite distinctive, although its detailed form appears to vary in time. Thus, the recent populations noted in the Brady Collection (from widely separated geographical localities) all appear to possess a broadly similar final chamber which is more radially elongate than those from Tertiary horizons. Furthermore, the later chambers of the recent specimens are much less embracing and the primary and supplementary apertures on the later chambers are considerably both higher and broader than those of their fossil counterparts. These characters can be of stratigraphic use. In Upper Miocene to recent times, the distal end of the final chamber (occasionally that of the penultimate as well) often becomes pointed, forming a narrow digitate extension; these narrow digitate extensions may become multiple on the final chamber during the Upper Sarmatian (see Hamilton and Rex, 1959, pl. 254, fig. 14) to Recent, and show a passage to forms described by Schubert (1910, 1911) as Globigerina /istulosa. In this latter form these digitate extensions may be present on all chambers of the last whorl and become long ""finger-like"" processes highly reminiscent of the chamber extensions seen in some Cretaceous genera (see Cushman, Todd and Post, 1954, p. 369, pl. 91, fig. 13).

Forms similar to the figured lectotype (pl. 4, figs. la, b) have been recorded by Bolli (1957, p. 113, pl. 25, figs. Sa-c), and by Blow (1959, p. 188, pl. 11, figs. 63a-b) in Miocene sediments and probably range from the Middle or Upper Aquitanian. Similar forms to these also occur in the type Tortonian of Nussdorf (Austria) and are known to range to the recent. Howtures than does G. quadrilobatus. However, forms ever, forms similar to Brady's ideotype, here figured, (pl. 4, figs. 2a-b) do not seem to occur before the Pliocene at least, and probably do not appear until the upper part of this interval. The fistulose forms may be restricted to Sarmatian to recent times. The earlier part of the test, up to and including much of the last whorl, is virtually identical to the species Globigerina quadri lobata d'Orbigny (see pl. 4, figs. 3a, b). The morphological type represented by Globigerinoides sacculiferus (Brady) var. irregularus LeRoy 1944 seems to form a ""connecting link"" between Globigerinoides quadrilobatus (d'Orbigny) and Globigerinoides sacculifer (Brady) but this form of LeRoy does not appear to have any great stratigraphic significance. Although Bolli (1957, p. 99, range chart) implies that ""G. triloba immatura"" (reete, G. quadrilobatus) and ""G. triloba sacculifera"" appear simultaneously within the Globorotalia kugleri Zone, Cipero formation (= Middle Aquitanian) there is, in fact, an interval of time between the appearances of these two forms, G. quadrilobatus appearing earlier, and this is implied by Blow (1959, p. 105, text-fig. 5), and indicated in text-figure 1.

It has been suggested (e. g., Hofker, 1959) that certain morphological characters used in the taxonomic differentiation of the Globigerinaceae are reproductive structures of no fundamental taxonomic importance. The ""sac-like"" nature of the later chambers of Globigerina sacculifera Brady might be considered in this light. However, we are firmly of the opinion that, whether or not this is the case, the ""sac-like"" final chamber is constant in form for any particular population and given instant of time, and, moreover, it is a developing character (as shown above) which is recognisably modified during evolution and thus must be an inheritable character with a genetic significance. Even if this character is associated with a reproductive phase its development and modification in time indicate that the organism is achieving a greater capacity to produce the ""sac-like"" final chamber with time, and thus it must be sensitive to the mechanics of natural selection and genetics and be of some taxonomic importance. Further, a new stock (the fistulose forms) appears to develop in the Mio-Pliocene from G. sacculifera, illustrating the new genetic potentialities of this form. However, we are not yet satisfied that characters such as these are wholly connected with a reproductive phase, for no direct biological evidence exists to support th:s point of view; these characters may be of an iterative nature and be connected with an environmentally adaptive process (see Banner and Blow 1959, 1960). As noticed above, "" Globigerinoides triloba altiapertura"" Bolli differs from Globigerinoides quadrilobatus (d'Orbigny) in possessing distinctly larger apertures. The early parts of the test of typical Globigerinoides sacculifer (Brady) also possess larger aper which are referable to primitive G. sacculifer and which occur contemporaneously with ""G. triloba altiapertura"" have smaller apertures, which are similar to those of G. quadrilobatus, than those seen in the recent specimens of G. sacculifer. It appears that, during the evolution and range of G. sacculifer, both the primary and supplementary apertures increase in size with time, so that it is the later forms (from younger horizons) that show the similarity of apertural shape to the Aquitanian ""G. triloba altiapertura."" Consequently, we regard the evolution of G. sacculijer to be independent of ""G. triloba altiapertura,"" because those apertural characters which they possess in common have been clearly acquired independently at two different periods of time; this is an example of iterative development of a morphological character within a closely related group of forms (compare Banner and Blow 1959, 1960). Also, as the gradual acquisition of larger apertures takes place in the G. sacculifer stock, but does not occur over the same stratigraphic interval in G. quadrilobatus sensu stricto, we consider that these two forms have followed separate lines of evolution since their first appearance in the middle part of the Aquitanian. Therefore, as G. sacculifer has evolved separately from G. quadrilobatus since its initial origin from the latter form, we believe that it is unlikely that one should represent a reproductive form of the other, and that they may be distinguished subspecifically. Preferred bathymetric habitats (see Emiliani, 1954) may account in part for their thanatocoenetic co-existence.

The two nomina nuda, Globigerina sacculifera Brady variante recumbens and G. sacculifera Brady variante galeata, both illustrated by Rhumbler 1911 (pl. 31, figs. 11-13 and 14-15 respectively) but not named until 1949 (in Wetzel, p. 39), are probably fully synonymous with G. sacculifera Brady 1877. It is perhaps noteworthy, in view of the above remarks, that the biologist Rhumbler, who examined these forms taken in vivo and who made cytological studies of his specimens whenever they were of interest, noticed no association between the ""sac-like"" chambers of this species and any part of a reproductive cycle. [Banner & Blow 1960]

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