. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. IIELIOZOA. 1S7 1. Imperforata. With membranous or calcareous shell, which is without fine pores, but possesses, in one place, an opening, either simple or sieve-like, through which the pseudopodia project. To these belong the GromidfP, with a mem- branous chitinous shell : Gromia or If or mis Duj., and Miliolidtf, with a porcellanous shell : Cornuspiraplanorl>is M. Sch., Miliola cyclostoma M. Sch., from the Miliolite chalk. 2. Perforata. The shell, which is usually calcareous, is invaria
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. IIELIOZOA. 1S7 1. Imperforata. With membranous or calcareous shell, which is without fine pores, but possesses, in one place, an opening, either simple or sieve-like, through which the pseudopodia project. To these belong the GromidfP, with a mem- branous chitinous shell : Gromia or If or mis Duj., and Miliolidtf, with a porcellanous shell : Cornuspiraplanorl>is M. Sch., Miliola cyclostoma M. Sch., from the Miliolite chalk. 2. Perforata. The shell, which is usually calcareous, is invariably pierced with innumerable fine pores as well as by one larger opening, and has complicated passages in the partition walls of its chambers. The La-geniJce have a hard shell, with a large opening surrounded by a toothed lip : Lagena vulgar is Williamson. The Globigerinidce on the contrary have a hyaline shell pierced by large pores, and a simple slit-like open- ing : Orlulina universa D'Orb., Ghibif/crina bulloides D'Orb., Ilutnliti D'Orb., Textularia D'Orb. The greatest size is attained by the JVum»iiiU/iifl(p, which possess a firm shell and an in- ternal skeleton, which last is pierced by a complicated canal system : Polystomella Lam., Niiinmulina D'Orb. Order 2.—HELIOZOA.* Fresh-water Rhizopods usually with pulsating vacu- ole, and one or more nuclei. A radial silicious skeleton sometimes present. The sareode body sends out in all directions tough radiating pseudopodia (fig. 128). When a skeleton is secreted, it consists either of radially arranged silicious spines (Acanthocystis) or of latticed silicious shells (Clathrulina), and so closely resembles the skeleton -of the Radiolaria that the Heliozoa have been actually described as fresh-water Radiolaria, They differ from the Radiolaria in the absence of the complicated * L. Cienkowski, " Ueber Clathrulina" Arcliio. fur mikrosb. Anatomic, Tom III., 1867. R. Greeff, " Ueber Radiolarien und radiolarienahnli
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