COLLEGE ZOOLOGY 



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

 ranged pseudopodia, which are usually supported by axial 



threads (Fig. 18, a). Ex- 

 amples: Actinosph&rium, Ac- 

 tinophrys (Fig. 18). 



Actinophrys (Fig. 18), the 

 sun animalcule, lives among 

 the aquatic plants in fresh- 

 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 



FIG. 18. Actinophrys sol, a HELIO- ,1 , , j ,. , 



ZOON. An individual with a large gastric the bod y> and are engulfed; 



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



axial filaments (a) in the raylike pseudo- , i i 



podia. (From Calkins, after Grenacher.) m b Y several ^ neighboring 



pseudopodia acting together. 



Order 3. Radiolaria. Marine RHIZOPODA with raylike 

 pseudopodia, a central perfor- 

 ated capsule of chitin (Fig. 19, 

 sk. j), and usually a larger en- 

 closing skeleton of silica (sk. i, 

 sk.2). Examples: Actinomma 

 (Fig. 19), Thalassicolla, Heli- 

 osphcera. 



The shells of the radio- 

 larians, upon sinking to the 

 sea bottom, form radiolarian 

 ooze; this becomes hardened, 

 producing rock strata as much 



as TOOO feet thirk These FlG ' I9> ~ Actinomma aster acanthion, 



ICK - 6 a RADIOLARIAN. The shell is broken 



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



miart7itps flint r>r rhprt rnn middle (5*. 2), and inner (5*. 3) spheres. 

 quartZltCS, n nt, O - (FrQm WeysSGj after H aeckel and 



cretions. Hertwig.) 



SK.2 



