7 6 



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. 



B. 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. 



Fig. 22. Collozoum inerme. A, B, C, three forms of colony ; D, small colony with central 

 capsules (c.caps), containing nuclei, and alveoli (vac) in ectoplasm; E, isospores, 

 with crystals (c) ; F, anisospores ; nu, nucleus. (From Parker and Haswell.) 



II. Osculosa (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. Nassellaria (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. ; Tripylaea, 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 "). 



