RHIZOPODA. -7 



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 Actinoplirys sol, which is round, with numerous stiff 

 pseudopodia radiating in all directions from the body, and 

 by Actinosphserium (Fig. 16). The true marine Radlolaria 

 &XQ represented by CoUosphmra 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 G. 



Class II.— rJIIZOPODA. 



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 raciiolei ; Tnomngiy means of pseudopodia, and 

 either naked or secreting a one or many-chambered sliell ; reproducing hy 

 ^elf-dimsion, or hy the production of several or many ammboid or monad- 

 Mke 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, sliells. 

 (Amoeba, Globigerina, Nummulina.) 



iOrder 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 hy a mem- 

 branous capsule with porous walls. Reproduction occurs 

 by the breaking up of the body into monad-like embryos, 

 with one or sometimes two locomotive lashes (flagella). 

 There are two divisions ; {l)Eeliosoa (Actinophrys, Actino- 

 sphaerium), and (3) Radiolaria (or Cytophora), having as rep- 

 resentatives Acanthometra, Collozoiim, Sphserozoum, and 

 CoUosphsera. 



