RHIZOPODA. QT 
of varied forms, more or less spherical, perforated for the 
protrusion of the pseudopodia, with often spicules or points 
radiating from the shell. They reproduce apparently by 
self-division of the interior, resulting in a swarm of monad- 
like young. The Heliozoa are represented by the fresh- 
water Actinophrys sol, which is round, with numerous stiff 
pseudopodia radiating in all directions from the body, and 
by Actinospherium (Fig. 16). The true marine Radiolaria 
are represented by Collosphera spinosa Cienkowski (Fig. 15). 
It possesses a perforated shell beset with small spines, which 
encloses a capsule with a protoplasmic wall. In the capsule- 
stage (A) it often divides by fission into two halves. After- 
ward the older capsule divides into a number of little round 
bodies, which develop two lashes as in C. 
Cuass IIl.—RHIZOPODA. 
Unicellular organisms consisting of protoplasm, with an outer clear, 
cortical, and an inner granular mass containing one or more nuclei, and 
one or more contractile vacuoles ; moving by means of pseudopodia, and 
either naked or secreting a one or many-chambered shell ; reproducing by 
self-division, or by the production of several or many ameabdoid or monad- 
like young. 
Order 1. Foraminifera.—One-celled Rhizopods with one or many nuclei 
and contractile vacuoles, usually secreting chambered cal- 
careous or horny (chitinous ?), rarely arenaceous, shells. 
(Ameeba, Globigerina, Nummulina.) 
Order 2. Radiolaria.—Rhizopods with pointed, branched, usually anas- 
tomosing and granular pseudopodia. The body contains 
either numerous small heterogeneous nuclei, or a single 
larger, highly differentiated vesicular nucleus. The pro- 
toplasm of the body is further separated into a peripheral 
non-nucleated and a central nucleated portion by a mem- 
branous capsule with porous walls. Reproduction occurs 
by the breaking up of the body into monad-like embryos, 
with one or sometiines two locomotive lashes (flagella). 
There are two divisions : (1) Heliozoa (Actinophrys, Actino- 
spherium), and (2) Radiolaria (or Cytophora), having as rep- 
resentatives Acanthometra, Collozotim, Spherozotim, and 
Collosphera. 
