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 {c.caps), 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 

 accumulation of dusky pigment granules (" phaeodium "). 



