. The microscope and its revelations. t ,SV/. vol. xix. 1879, p 20, andvol. xxi. 1881, p. 31. 812 MICROSCOPIC FORMS OF ANIMAL LIFE families, the first of which, Astrorhizida, includes with the precedinga number of coarse sandy forms, usually of considerable size, andessentially monothalamous. though sometimes imperfectly chamberedby constrictions at intervals. Some of the more interesting examplesof this family will now be noticed, beginning with the Saccammina (Sars), which is a remarkably regular type, composed of coarse sand-grains firmly cemented together in a globular form
. The microscope and its revelations. t ,SV/. vol. xix. 1879, p 20, andvol. xxi. 1881, p. 31. 812 MICROSCOPIC FORMS OF ANIMAL LIFE families, the first of which, Astrorhizida, includes with the precedinga number of coarse sandy forms, usually of considerable size, andessentially monothalamous. though sometimes imperfectly chamberedby constrictions at intervals. Some of the more interesting examplesof this family will now be noticed, beginning with the Saccammina (Sars), which is a remarkably regular type, composed of coarse sand-grains firmly cemented together in a globular form, so as to constitutea wall nearly smooth on the outer, though rough on the inner surface,with a projecting neck surrounding a circular mouth (fig. 613, a, b,c). This type, which occurs in extraordinary abundance in certainlocalities (as the entrance of the Christiania fjord, and still furthernorth on the shores of Franz Josef Land), is of peculiar interestfrom the fact that a closely allied species (Saccdnvmina Carter!) - FIG. 613.—Arenaceous Foraminifera : a, Saccammina xjihu rim ; b, the samelaid open ; c, portion of the test, enlarged to show its component sand-grains ; d, Pilulina Jijfrrymi; e, portion of the test enlarged, showingthe arrangement of the sponge-spicules. as Mr. H. B. Brady has shown, one of the chief constituents ofcertain beds of the Lower Carboniferous limestone of the north ofEngland and elsewhere. In striking contrast to the preceding isanother single-chambered type, distinguished by the whiteness ofits test, to which the Author has given the name of I-ilnlt/ia, fromits resemblance to a homoeopathic globule (fig. 613, d, e). Theform of this is a very regular sphere ; and its orifice, instead ofbeing circular and surrounded by a neck, is a slit or fissure withslightly raised lips, and having a somewhat S-shaped curvature. Itis by the structure of its test, however, that it is especially dis-tinguished ; for this is composed of the finest ends of s
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