5, _Hastigerina murrayi_, Wyv. Thomson, a, Bubbly (vacuolated) protoplasm, enclosing b, the perforated _Globigerina_-like shell (conf. central capsule of Radiolaria). From the peripheral protoplasm project, not only fine pseudopodia, but hollow spines of calcareous matter, which are set on the shell, and have an axis of active protoplasm. Pelagic; drawn in the living state. 6, _Globigerina bulloides_, d'Orb., showing the punctiform perforations of the shell and the main aperture. 7, Fragment of the shell of _Globigerina_, seen from within, and highly magnified, a, Fine perforations in the inner shell substances; b, outer (secondary) shell substance. Two coarser perforations are seen in section, and one lying among the smaller. 8, _Orbulina universa_, d'Orb. Pelagic example, with adherent radiating calcareous spines (hollow), and internally a small _Globigerina_ shell. It is probably a developmental phase of _Globigerina_, a, _Orbulina_ shell; b, _Globigerina_ shell. 9, _Polytrema miniaceum_, Lin.; X 12. Mediterranean. Example of a branched adherent calcareous perforate Recticularian. 10, _Calcarina spengleri_, Gmel.; X 10. Tertiary, Sicily. Shell dissected so as to show the spiral arrangement of the chambers, and the copious secondary shell substance. a^2, a^3, a^4, Chambers of three successive coils in section, showing the thin primary wall (finely tubulate) of each; b, b, b, b, perforate surfaces of the primary wall of four tiers of chambers, from which the secondary shell substance has been cleared away; c', c', secondary or intermediate shell substance in section, showing coarse canals; d, section of secondary shell substance at right angles to c'; e, tubercles of secondary shell substance on the surface; f, f, club-like processes of secondary shell substance.] _Historical._--The Foraminifera were discovered as we have seen by A. d'Orbigny. C.E. Ehrenberg added a large number of species, but it was to F. Dujardin in 1835 that we owe the recognition of their true zoological position and the characters of the living animal. W.B. Carpenter and W.C. Williamson in England contributed largely to the study of the shell, the latter being the first to call attention to its multiform character in the development of a single species, and to utilize the method of thin sections, which has proved so fertile in results. W.K. Parker and H.B. Brady, separately, and in collaboration, described an enormous number of forms in a series of papers, as well as in the monograph by the latter of the Foraminifera of the "Challenger" expedition. Munier-Chalmas and Schlumberger brought out the fact of dimorphism in the group, which was later elucidated and incorporated in the full cytological study of the life-cycle of Foraminifera by J.J. Lister and F. Schaudinn, independently, but with concurrent results.