... characterized by septate chambers ( Heterostegina depressa, Planostegina operculinoides , and Cycloclypeus carpenteri ) either group with species lacking septate chambers ( Operculina ammonoides, Nummulites venosus ) or branch separately. This suggests that chamber subdivisions developed several times...

... are Operculina ammonoides , Heterostegina depressa , and Palaeonummulites venosus and fossil taxa used are Nummulites perforatus , N. fabianii , and N. tavertetensis (only A forms were used in this study). Our results seem to differentiate the hydrodynamic behavior of shells collected from banks from those...

...TEXT-FIGURE 2 Scanning micrographs of operculinid foraminifera. 1. Operculina ammonoides (Gronovius), Sesoko Transect, sample Sesoko-11/1, 40m depth; 2. Operculina elegans Cushman, Minna Jima Transect, 40m depth; 3. Operculina complanata (Defrance), Sesoko Transect, sample Sesoko-4, 60m...

...Figure 1 Axial section parameters measured in Operculina ammonoides (shown) and other species (see Table 1 ). Chamber lumen area (in gray) and center of gravity (x) for each half whorl must be obtained by image analysis. Circles represent identical area of each half-volution lumen...

... and others, 1999 ). 7–9 Operculina ammonoides (Gronovius), semiinvolute form, lateral and axial views, specimens from 19 m in the lagoon NE of Sesoko Island. 10–12 Operculina ammonoides (Gronovius), evolute form with strong sculptures, specimens from 30 m depth south of Amakusa Island (Fig. 1 ). All...

...F igure 16. Competition between Operculina ammonoides – O. complanata, and between Planostegina longisepta–P. operculinoides at the northern transect of Sesoko Island. ...