FORAMINIFERA, an order of ani mals belonging to the sub-kingdom Pro tozoa, and the class RHIZOPODA (q. v.). The body is contained within a calcare ous test or shell, which is polythalamous (many-chambered). It may be cylindrical or spiral, or it may tend to the pyramidal form. The outer surface presents a punc tate or dotted appearance, produced by the presence of very numerous foramina, or small apertures. Foraminifers are always of small size, and often indeed microscopic. With the exception of Groniia, which occurs both in fresh and salt water, they are exclusively marine. Sometimes their shells constitute sea sand. In the Atlantic, at a depth of 3,000 fathoms, there is an ooze composed al most entirely of Globigerinte, which be long to this order; the stratum thus formed is a direct continuation of the white chalk deposit, having gone on ap parently through the whole Tertiary period. Drs. Carpenter and Parker, and
Prof. T. Rupert Jones have divided the thus: Sub-order I.—Imperforate. Families: (1) Gromida, (2) Miliolida, (3) Lituo lida.
Sub-order IL—Perf orate. Families: (1) La genida, (2) Globigerinida, and (3) Numm2flinida.
The exceedingly antique Eozoon of the Laurentian rocks, if organic, as it is generally believed to be, was apparently a foraminifer. Forms more unequiv ocal, some of them very like recent species, occur in the Silurian, the Car boniferous, and other strata. They are found through all the Secondary period. chalk being almost entirely composed of their cases. They increase in number and importance in the Tertiary. The num mulites of the Midde Eocene are forami niferous animals.