Contribution to the knowledge ofRzehakinaCushman (Foraminifera) in New Zealand

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Abstract
Rzehakina Cushman first appears in the lower Raukumara Series (lower Senonian) becoming widespread and abundant in the Haumurian and Teurian prior to its extinction in lower Dannevirke time (Paleocene). The problem of variability within the genus has been approached by analysing samples in terms of prolocular size, gross dimensions and coiling. Distinction of generational forms is basic to this approach. Early Haumurian samples contain two generations separable only upon their prolocular dimensions. I,ater Haumurian and Teurian samples reveal progressive attenuation in the shape of the microspheric generation together with rotation of planes of coiling of early chambers, The megalospheric generation throughout maintains stability in shape dimensions, A third form, considered a further microspheric generation but exhibiting morphological stability, ranges from upper Haumurian into T,eurian strata, All forms are rderred to Rzehakina epigona (Rzehak) pending closer investigation of this species.

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