54 FORAMINIFERA 



6. Test trochoid at least in the young. 



a. Mostly free and typically trochoid throughout. 



Family 19. Trochamminidae. 



b. Attached, young trochoid, later stages variously formed. 



Family 20. Placopsilinidae. 



c. Free, conical, mostly of large size. 



Family 21. Orbitolinidae. 



7. Test coiled in varying planes, wall imperforate, w^ith arena- 



ceous portion only on the exterior. 



Family 16. Miliolidae (in part). 



III. Test calcareous, imperforate, porcellanous. 



A. Test with the chambers coiled in varying planes, at least in the 



young, aperture large, toothed. Family 16. Miliolidae (in part). 



B. Test trochoid Family 18. Fischerinidae. 



C. Test planispiral, at least in the early stages. 



1. The axis very short, chambers usually simple. 



Family 17. Ophthalmidiidae. 



2. The axis short, test typically compressed and often discoid, 



chambers mostly with many chamberlets. 



Family 26. Peneroplidae. 



3. The axis typically elongate, chamberlets developed. 



Family 27. Alveolinellidae. 



D. Test globular, apertures small, not toothed. 



Family 28. Keramosphaeridae. 



IV. Test calcareous, perforate. 



A. Test vitreous with a glassy lustre, aperture typically radiate, not 



trochoid. 



1. Test planispirally coiled or becoming straight, or single 



chambered Family 22. Lagenidae. 



2. Test biserial or elongate spiral. Family 23. Polymorphinidae. 



B. Test not vitreous, aperture not radiate. 



1. Test planispiral, occasionally trochoid, then usually with 



retral processes along the suture lines, septa single, no 

 canal system Family 24. Nonionidae. 



2. Test planispiral, at least in the young, generally lenticular, 



septa double, canal system in higher forms. 



Family 25. Camerinidae. 



3. Test at least in the microspheric form of most genera biserial, 



aperture usually large, without teeth. 



Family 29. Heterohelicidae. 



4. Test planispiral, bi- or triserial with elongate spines and 



lobed aperture Family 30. Hantkeninidae. 



5. Test typically with an internal tube, elongate. 



a. Aperture generally loop-shaped or cribrate. 



Family 31. Buliminidae. 



b. Aperture narrow, curved, with an overhanging portion. 



Family 32. Ellipsoidinidae. 



