"The lamellar foraminifera, which construct their tests by the addition of lamellae of perforate calcite or aragonite, one per instar, covering the whole test, are here recognized as a distinct group and are separated from the non-lamellar foraminifera, which construct their tests by the simple addition, at each instar, of a chamber on the former apertural face. . . . The present classification is based on anatomy, composition and texture of the chamber walls, apertural characters and tooth-plates, canal systems, and chamberarrangement. Although essentially not a phylogenetic ('vertical') one, the present classification supports Hofker's conclusions to a great extent."