THE Foraminifera constitute a class of Protozoa which provides many problems of great interest for the morphologist, the systematist, and the palaeontologist. Their remarkable life history, the beauty and elaboration of their shells, and the records of their occurrence in the rocks from the most ancient times have been the subjects of many elaborate and important treatises in recent times. It is difficult for anyone to follow the progress of our knowledge of the group in all these directions; but as in other groups of animals, it is the work of the systematists which is most usually set aside as suitable only for the perusal of the specialists.
E. Heron-Allen and A. Earland . On the Pegididæ, J. Roy. Micr. Soc., 1928. Vol. 48. Some New Foraminifera from the South Atlantic, Parts I., II., and III. Ibid., 1929; 1930. Vols. 49 and 50.
J. Hofker, Foraminifera of the Siboga Expedition, Part II.; 1930.