Globigerinina

From Foraminifera

Planktonic in habit; test wall of perforate hyaline calcite, optically radiate, preferred crystal orientation with c-axis normal to surface; primary lamination bilamellar, second­ary lamination due to addition of shell material during formation of new chamber; surface crust may develop at time of gametogenesis. M. Jurassic (Bathonian) to Holocene.

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after Loeblich & Tappan (1988)