86 Subsurface Geologic Methods 



FORAMINIFERA 



The Foraminifera (fig. 36) are single-celled, microscopic animals be- 

 longing to the phylum Protozoa. These forms, ranging in diameter from 

 0.01 mm. to 50.0 mm., attain their best development in marine environ- 

 ments, although some genera and species occur profusely in brackish- and 

 even fresh-water habitats. Their tests (shells) are extremely variable in 

 structure and composition. Certain genera secrete chitinous, arenaceous, 

 and siliceous tests, although most of them produce calcareous structures. 

 Tests of the Early Paleozoic Foraminifera are structurally simple; those 

 of the Mesozoic and Cenozoic exhibit more complexity and variety. Fora- 

 minifera occur abundantly locally in the Late Paleozoic deposits and even 



EXPLANATION OF PLATE 1 



Figure 

 1- 3. Cibicides telisaensis LeRoy X 82. Fig. 1, ventral view. Fig. 2, dorsal view. 



Fig. 3, peripheral view. 

 4- 6. Anomalina sp. A LeRoy X 75. Figs. 4, 5 opposite sides. Fig. 6, peripheral 



view. 

 7- 9. Cibicides dorsopustulosus LeRoy X 43. Fig. 7, dorsal view. Fig. 8, ventral 



view. Fig: 9, peripheral view. 

 10-12. Cibicides foxi LeRoy X 75. Fig. 10, dorsal view. Fig. 11, ventral view. Fig. 



12, peripheral view. 

 13-15. Anomalina sp. A LeRoy X 65. Figs. 13, 15, opposite sides. Fig. 14, peripheral 



view. 

 16-18. Cancris auriculas (Fichtel and Moll) X 47. Fig. 16, dorsal view. Fig. 17, 



ventral view. Fig. 18, peripheral view. 

 19-21. Valvulineria aff. inaequalis (d'Orbigny) X 75. Fig. 19, dorsal view. Fig. 20, 



ventral view. Fig. 21, peripheral view. 

 22-24. Eponides praecintus (Karrer) X 35. Fig. 22, dorsal view. Fig. 23, ventral 



view. Fig. 24, peripheral view. 

 25-27. Quinqueloculina sp. H LeRoy X 29. Figs. 25, 26, opposite sides. Fig. 27, 



apertural view. 

 28-30. Valvulineria araucana (d'Orbigny) car. malagaensis Kleinpell X 47. Fig. 28, 



dorsal view. Fig. 29, ventral view. Fig. 30, peripheral view. 

 31-33. Baggina inflata LeRoy X 47. Fig. 31, dorsal view. Fig. 32, ventral view. 



Fig. 33, peripheral view. 

 34-36. Globorotalia barissanensis LeRoy X 73. Fig. 34, peripheral view. Fig. 35, 



dorsal view. Fig. 36, ventral view. 

 37, 38. GlobigerineUa aequilateralis (Brady) X 48. Fig. 37, side view. Fig. 38, per- 

 ipheral view. 

 39, 40. Globigerina siakensis LeRoy X 54. Fig. 39, dorsal view. Fig. 40, ventral view. 



41,42. Globigerinoides trilocularis (d'Orbigny) X 37. Fig. 41, ventral view. Fig. 42, 



dorsal view. 

 43, 44. Globigerina baroemoenensls LeRoy X 41. Fig. 43, dorsal view. Fig. 44, ventral 



view. 

 45,46. Globigerinoides sacculiferus (Brady) var. irregularus LeRoy, n. var. X 39. 



Opposite views. 



more so in strata of Mesozoic and Cenozoic age. It is not uncommon to 

 find limestones and marlstones of the Pennsylvanian and Permian com- 

 posed almost entirely of the remains of these organisms (fusulinids) . 

 Many Cretaceous chalks and Eocene limestones contain multitudes of 

 foraminiferal tests as well as numerous argillaceous deposits of the Late 

 Tertiary (fig. 36), which accumulated under tropical or subtropical con- 

 ditions. 



