STUDIES IN FORAMINIFERA 



1^ 



Globigerino grtmsdolet 



Globoquodrina quadraria 



10 20 30 40 50 60 70 80 90 100% 



Globigerino Venezuelono 



CotapsydrM dissimllis ■ 



Figure 7. — Percentage of sinistral coiling of some Oligocene-Miocene 

 Orbulinidae, showing dominantly sinistral coiling in later development 

 of certain species of Globigtrina, Globigerinoides, and Globoquodrina, 

 and dominantly dextral coiling of Catapsydrax. (Modified after BoUi, 

 195 1). 



Figure 8. — Provinces of dominantly sinistral and dextral coiling of living 

 Globorotalia truncatulinoides populations. (After Ericson, G. Wollia 

 and J. Wollin, 1954). 



syzygy of megalospheric individuals before the produc- 

 tion of the gametes of the sexual generation. This 

 syzygy in the case of Patellina was thought to ensure 

 completion of the reproductive processes, as the gametes 

 were amoeboid and nonflagellate. However, other 

 species also show syzygy which do develop flagellate 

 gametes. The coiling direction might facilitate this 

 process, as firm adherence of two tests by their lun- 

 bilical sides is possible only between individuals of the 

 same direction of coiling. According to Vasicek, the 

 extremes in coiling ratios may thus be due to absolute 

 dependence of the reproductive processes upon such 

 syzygy, during relatively unfavorable conditions, and 

 the fluctuations noted in cores may be due to mixing 

 of populations from another province. In the Mora- 

 vian region, the coiling ratio curves were somewhat 

 different in the deeper portions of the basin, suggesting 

 the possibility of an influence of temperature. 



These theories can only be suggested on the basis of 

 fossil material and to date very little experimental 

 work has been done on life histories and processes of 

 planktonic Foraminifera, due to the considerable dif- 

 ficulty encountered in propagating them under con- 

 trolled laboratory conditions. 



Systematics 



Historical Summary 



In the classification of d'Orbigny, based solely upon 

 chamber shape, the planktonic genera would fall into 

 four of his seven orders. Orbulina would be placed in 

 the Monostegues, or single chambered forms. Olobig- 

 erina and other trochospiral forms would belong to the 

 H^licostegues (or helically coiled forms), Cassigerinella 

 (though then as yet unknown) would have been placed 

 with Cassidulina in the Entomostegues and Sphaeroid- 

 inella in the Agathistfigues. 



Carpenter (1862) included in the family Globiger- 

 inida all coarsely perforate forms, considering Orbvlina 

 to be the ancestral and simplest form. However, in 

 the Globigerinida he also included with the Globiger- 

 inae the arenaceous Textularinae, the Bulimina group 

 (with complex internal tubes), and the Rotalinae (with 

 complex canal systems) ; so that his "coarsely perforate" 

 family included those with perforations of widely dif- 

 fering character, origin, and structure. 



Brady (1884) restricted the Globigerinidae to include 

 only Qlohigerina, Orbulina, Hastigerina, PuUenia, Sphae- 

 roidina, and Candeina. Other planktonic forms were 

 referred to Pulvinulina [Globorotalia] in the Rotaliidae. 



Cushman (1928) separated the then described genera 

 which are included in the present study, into three 

 families, the Globigerinidae, Globorotaliidae, and Hant- 

 keninidae. He included in the family Globigerinidae 

 the subfamilies Globigerininae, Orbulininae, Pullenia- 

 tininae, and Candeininae. The first of these subfami- 

 lies was quite inclusive, with genera of many varying 

 characters, some of which are here placed in the family 

 Hantkeninidae. Each of the last three subfamilies 



