30 



PROTOZOA RHIZOPODA 



CLASS I 



Family 3. G-lobigerinidae. Carpenter. 



Test free, calcareous, perforated by coarse tubules; monothalamous or poly- 

 thalamous ; chambers globular, either irregularly disposed or imperfectly spiral. 



Of the two most important genera belonging to this family, Orbulina, d'Orb. 

 (Fig. 32, A}, is unilocular, and GloUgerina, d'Orb. (Fig. 32, C], multilocular. The 



individual chambers 

 usually conduct into a 

 common central'canal. 

 In both genera the test 

 is often covered with 

 extremely delicate 

 calcareous spines, 

 which, however, are 

 very easily broken 

 off, and are never 

 preserved in the fossil 



Austriaca, d'Orb. Miocene Tegel ; Baden, near Vienna. ' C, GloUgerina con- State. These genera 

 fjlomerata, Schwager. Pliocene; Kar Nikobar Island, a, Inferior surface; QT , A AYPAcivpli7 rliflfncp 

 b, Superior surface ; c, Portion of periphery ; d, Transverse section enlarged. ' e v L 



in modern deep-sea 



deposits (Globigerina ooze) ; they occur sparingly in Mesozoic formations, 

 beginning with the Triassic, and first rise to importance during the late 

 Tertiary period. 



Sphaeroidina, d'Orb. (Fig. 32, B}. Cretaceous to Recent. 



FIG. 32. 



Family 4. Botalidae. Carpenter. 



Test calcareous, rarely arenaceous or silicious, finely or coarsely perforated, fre- 

 quently with intermediate skeleton, free or attached, turbinate or discoidal in contour. 

 Segments usually arranged in an elongated spire, although in some forms 



Discorbina, Park. Jones (Fig. 33, A, B). Test coarsely perforated, tur- 

 binoid. Inferior surface broad and flat ; umbilicus often filled with deposit 

 of intermediate skeleton. Cretaceous to Recent. 



Planorbulina, Park. Jones (Fig. 33, C). Test coarsely perforated, com- 

 planate, usually attached, superior and inferior, surfaces dissimilar ; early seg- 

 ments arranged in depressed spire, subsequently becoming cyclical. Lias to 

 Recent. The d'Orbignyan sub-genera Truncatulina, Anomalina, Planulina, 

 etc., are based upon different modifications in form. 



jRotalia, Lam. (Fig. 34, A). Test finely perforated, with segments in 

 turbinoid spire. Septa composed of two slightly separated lamellae, .with 

 anastomosing canals occupying the intermediate space. Basis often 

 thickened by supplemental skeleton. (?) Silurian. Upper Jurassic to 

 Recent. 



Pulvinulina, Park. Jones (Fig. 34, B}. Rotaliform, but septa single and 

 without interseptal canal-system. Lower Lias to Recent. 



Endothyra, Phill. (Fig. 34, C). Test calcareous ; composed of an exterior 

 coarsely perforated, and an interior compact layer consisting of minute grains 

 of limey matter ; polythalamous ; irregularly spiral. General aperture 



