COLLEGE ZOOLOGY 



Order 2. Heliozoa. - - RHIZOPODA with thin, radially ar- 

 ranged pseudopodia, which are usually supported by axial 



threads (Fig. 18, a). Ex- 

 amples: Actinosphcerium, Ac- 

 tinophrys (Fig. 18). 



Actinophrys (Fig. 18), the 

 sun animalcule, lives among 

 the aquatic plants in fresh- 



i 



water ponds and ditches. The 

 body appears vesicular, being 

 crowded with vacuoles (c). 

 The small organisms which 

 serve as food strike the 

 pseudopodia, pass down to 



ek.t 



FIG. rt.-- Actinophrys sol a HELIO- h fa d d are lfed 



ZOON. An individual with a large gastric J > 



vacuole (g), contractile vacuole (c), and larger organisms (g) are drawn 



axial filaments (a) in the raylike pseudo- . , c PV prfll neio-hboHno- 

 podia. (From Calkins, after Grenacher.) 



pseudopodia acting together. 



Order 3. Radiolaria. - - Marine RHIZOPODA with raylike 

 pseudopodia, a central perfor- 

 ated capsule of chitin (Fig. 19, 

 sk. ji), and usually a larger en- 

 closing skeleton of silica (sk. i, 

 sk.2). Examples: Actinomma 

 (Fig. 19), Thalassicolla, Heli- 

 osph(Era. 



The shells of the radio- 

 larians, upon sinking to the 

 sea bottom, form radiolarian 

 ooze; this becomes hardened, 

 producing rock strata as much 



r - 1 i rpii FIG. io. Actinomma asteracanlhion, 



as 1000 feet thick. These a RADIOLARIAN . T he shell is broken 



rocks may take the form of away so as to show the outer (sk. i), 

 , ., a - middle (sk. 2), and inner (sk. 3) spheres. 



quartzites, flint, or chert con- (From WeyssC( after Haeckel and 



CretionS. Hertwig.) 



SK.2 



