. The Cambridge natural history. Zoology. 76 PROTOZOA The following is Haeckel's classification of the Eadiolaria:—• PoRULOSA (HoLOTRyPASTA).—Homaxonic, or nearly so. Central capsule spherical in the first instance; pores numerous, minute, scattered ; mostly pelagic., A. Spumellaria (Peripylaea).—Pores evenly scattered ; skeleton of solid siliceous spicules, or continuous, and reticulate or latticed, rarely absent; nucleus dividing late, as an antecedent to reproduction. Acantharia (Actipylaea).—Pores aggregated into distinct areas ; skeleton of usually 20 centrogenous, regularly radiating spi
. The Cambridge natural history. Zoology. 76 PROTOZOA The following is Haeckel's classification of the Eadiolaria:—• PoRULOSA (HoLOTRyPASTA).—Homaxonic, or nearly so. Central capsule spherical in the first instance; pores numerous, minute, scattered ; mostly pelagic., A. Spumellaria (Peripylaea).—Pores evenly scattered ; skeleton of solid siliceous spicules, or continuous, and reticulate or latticed, rarely absent; nucleus dividing late, as an antecedent to reproduction. Acantharia (Actipylaea).—Pores aggregated into distinct areas ; skeleton of usually 20 centrogenous, regularly radiating spines of acanthin, whose branches may coalesce into a latticed shell; nucleus dividing early. B,. Fig. 22.—Gollozoum inerme. A, B, C, three forms of colony ; D, small colony with central capsules {), containing nuclei, ."ind alveoli (vac) in ectoplasm; E, isospores, with crystals (c) ; F, anisospores ; nu, nncleus. (From Parker and Haswell.) II. OsuuLOSA (Monotrypasta).—Monaxonic ; pores of central capsule limited to the basal area (osculum), sometimes accompanied by two (or more) smaller oscula at apical pole, mostly zonarial or abyssal. C. Nassellarta (Monopylaea).—Central capsule ovoid, of a single layer ; pores numerous on the operculum or basal field ; skeleton siliceous, usually with a principal tripod or calthrop-shaped spicule passing, by branching, into a complex ring or a latticed bell-shaped shell; nucleus eccentric, near apical pole. D. Phaeodaria (Cannopylaea, Haeck.; Tripylaba, Hertw.).—Central capsule spheroidal, of two layers, in its outer layer an operculum, with radiate ribs and a single aperture, beyond which protrudes the outer layer; osculum basal, a dependent tube (proboscis); accessory oscula, when present, simpler, usually two placed sym- metrically about the apical pole ; skeleton siliceous, with a com- bination of organic matter, often of hollow spicules; nucleus sphaeroidal, eccentric; extracapsular protoplasm containing an
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