812 



MICROSCOPIC FORMS OF ANIMAL LIFE 



families, the first of which, Astrorhizida, includes with the preceding 

 a number of coarse sandy forms, usually of considerable size, and 

 essentially monothalamous. though sometimes imperfectly chambered 

 by constrictions at intervals. Some of the more interesting examples 

 of 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 constitute 

 a 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 certain 

 localities (as the entrance of the Christiania fjord, and still further 

 north on the shores of Franz Josef Land), is of peculiar interest 

 from the fact that a closely allied species (Saccdnvmina Carter!) is. 



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FIG. 613. Arenaceous Foraminifera : a, Saccammina xjihu rim ; b, the same 

 laid open ; c, portion of the test, enlarged to show its component sand- 

 grains ; d, Pilulina Ji'jfrrymi; e, portion of the test enlarged, showing 

 the arrangement of the sponge-spicules. 



as Mr. H. B. Brady has shown, one of the chief constituents of 

 certain beds of the Lower Carboniferous limestone of the north of 

 England and elsewhere. In striking contrast to the preceding is 

 another single-chambered type, distinguished by the whiteness of 

 its ' test,' to which the Author has given the name of I'-ilnlt/ia, from 

 its resemblance to a homoeopathic 'globule' (fig. 613, d, e). The 

 form of this is a very regular sphere ; and its orifice, instead of 

 being circular and surrounded by a neck, is a slit or fissure with 

 slightly raised lips, and having a somewhat S-shaped curvature. It 

 is by the structure of its ' test,' however, that it is especially dis- 

 tinguished ; for this is composed of the finest ends of sponge-spicules. 

 very regularly ' laid ' so as to form a kind of felt, through the sub- 



1 For a detailed account of ,V. xj>lurrir consult L. Rhmnbler, in vol. Ivii. of Zeitschr. 

 f. wins. Zonl. 



